Why do people say gyms are so easy now?

for low level its hard but nowadays most people already reached lvl 30+ and poweredup thr pokemon. for me its very easy tho i only use 2 tyranitars to defeat gyms againts with blissey, dragonite, and etc.

It is area dependent, yes.
If you think dealing with Blissey is still a challenge, you probably don't deserve the "hardcore player" title.
I deal with ZH DG 3000+cp Blissey every day, and since people here are feeding like crazy, sometimes I need to kill a same pink fat b*tch over 30 times. Highly competitive area forces us hardcore players to build up the strongest armies, and then all that matters is whether you are willing to waste that much time, battery and energy on taking down a gym. As far as taking down a gym is concerned, it is not a can-or-can-not question, it is rather a worth-the-time-or-not question.
That's what we mean by "easy".

I rarely encounter someone actually feeding berries while I am fighting. So a gym with low motivation can be taken down by 1 single mon.

There is no challenge for me anymore. I'm level 37 and I have enough powered up Pokémon that I can blindly select any group of 6 out of my top 50 and probably take the gym down without worrying about dodging or type advantages. Now you add in the cp being lowered and the Pokémon get even easier to defeat. There is no strategy needed to take down any 2000cp Pokémon besides to continue tapping your screen. Top 12 attached not to show off but to help explain my point.

Actually, the gym scene go to extremes either too easy or hardly possible. The latter case is where the owner actually feeds and boost his mon to full health. I once failed to get rid of a single snorlax of cp2xxx in 30 or so mins and eventually I gave up (coupled with mobile hung )

The gyms have become easier because if you wait enough, even a noob could take them over when the motivation has depleted. Or otherwise anyone level 25+ can take over a gym that has a Blissey if they own a Machamp and something else as backup (Ursaring with fighting moves will do), and Fairies are easy to fight off, none are very strong. You add a Magneton or Steelix with steel moves or a Victreebel or Nidoking with poison moves to the team and they're out fast.

So you have trouble with Blissey? Gyms used to be 10 of them. The biggest reason they are easy is because I rarely face a fully motivated pokemon. I can typically use a single Dragonite to go through the entire gym. If the pokemon are fully motivated, there are only 6 in a gym, so you chose the BEST COUNTER for every single one.

Here is the best way to explain it...

I was a pretty hardcore before. I took down 1-2 level 10 gyms a day, maybe 3 if I recharged my phone. That would take 2-3 hours and all my resources.

Now I go around early morning and take down about 20 gyms. Last time I took down 23 (3 were retaken before I was done, for a total of 20.) It cost me a couple of potions and a handful of revives, because I did not need to use potions on my Pokemon, because I used them at half health. It costs about 1-2 revives per gym. I can do it on 1 battery charge.

So 2 gyms vs 23...

It's all relative to the old gym scene. Gyms used to be very time consuming with more quality defenders and no CP decay.

With vigilant dodging and no hard-counter matchups, I can get through most gyms with one fully powered Tyranitar and 3 Hyper Potions.

The hardest thing about gyms is, and always has been, the glitches and lag. I fought a gym last night whose defenders had all but one decayed to zero motivation, so I had to win 7 battles to clear the gym, ranging from 100 to 500 CP. It took me 45 minutes to win.

The first fight took a few seconds, like you'd expect, but then the second fight GPS drifted so far away that it kicked me out of the fight, then kept giving me error messages for ten minutes. Once it finally let me fight again, endless lag and network errors timed me out and forced me to restart the game multiple times for every single opponent, for battles that should have been over in seconds. Then once I was finally down to the last opponent (a Bayleef with 200-something CP the first fight) it GPS drifted me again, and I had to wait another ten minutes for it to let me try again.

This is why I don't fight gyms anymore, if I can avoid it, and always try to find ones with open slots for my team.

Remember when gen2 was first released and the gym scene was changed as well (for a short period of time). Blissey was actually tough, and fast moves were no longer 'fast'. Everyone complained, but I really liked it. It weeded out all of the casual players. Only hardcore players could survive in the gym scene.

Now... the scene is weak and caters to all the softies.

As long as no one feeds during attack, gyms are easy. Yes, there might be one blissey. You will need to concentrate for exactly one battle - until blissey is defeated first time. Rest is easy going.

Lately I've taken down gyms in 20 minutes, using only 10 Pokémon. And only 10 Pokémon because I didn't particularly care to dodge in the last 3 rounds of battles.

Without using a single one of the Pokémon I've powered up for Raid Battles (most of which are up around Level 30 now) or for defending gyms (So annoyed at all the time and Stardust I wasted on Snorlax and Blisseys). So most of my Pokémon are between level 20 and 30, with the level 30's being almost entirely Eevee evolutions (Jolteon and Vaporeon mostly). Just pick the right ones and gyms go down quick and easy, particularly when they get weaker every time they are defeated.

The only thing that keeps me from taking down gyms on a regular basis is that there's no incentive to take down more than 1 gym a day. Otherwise, I could take about 3 hours and easily take down the 10 gyms in walking distance from my home.

And I'm a piddly Level 34 with only about 10 Pokémon that are actually my level (and most of them are Golems, which aren't quite as useful in attacking gyms as they are in attacking Legendary's). I have 1 T-Tar who is Level 22, and 2 Dragonites who are Level 20 each - none of whom I used on any regular basis. The Gyms are a joke now.

I just pick the best counter for the first (first 2 if they line up) pokemon in the gym, run them over 3 times so they are kicked out, rinse and repeat, even if they are being G-Razz feed, they'll "run out" before you run out of attackers, I usually keep Blue and Pink (Healing my blisseys and use in raids) potions, and toss Purple and Yellow, so this let's me find a use for those (as I rarely have any of my attackers faint). The only annoying thing about this technique is when you randomly get locked out of the gym for a few minutes, sometimes giving them time to replace the defenders you knocked out, but still they won't last long.

Conquest gyms it's easy... defend them it's challenging.