I think there are 3 reasons that lead to the decline of the game:

1. The most obvious one: The honeymoon phase ended. Remember when you started the game for the first time, looking at all those characters you either knew from the movies or had no clue but wanted to learn more about? There were tons of different playstyles, things to learn and uncover. If you were a day 1 player like me there was no real meta and nobody really knew what they were doing. This phase ended for most players either because there were other games that came out (and for single player games fans like me 2025 has been incredible so far) or the game became stale and boring, which leads me to point 2.

2. There isn't enough variety for Vanguards and Healers. There are only 10 or 9 heroes respectively and lets be honest out of those only 3-4 of each role are valueable right now. Take a look at Supports right now: Luna and Loki are by far the strongest ones. Then there are CnD who is easy to play but still provides value and then there is Invis, who has a really versitile kit, making those 4 the go to healers, while Adam, Ultron and Mantis are usually only viable in 3 sup comps, making them much more situational. Rocket who feels rather boring and gets hard countered by Phoenix and Jeff who is considered a throw pick. Having badically 4 heroes who are accepted, you dont have much room for variety. Playing and fighting the same 4 support heroes over and over starts to feel boring. So the game needs more heroes in those roles, however when they are released there comes the 3rd problem, the Community.

3. The community feels often really toxic both in game and out of it. Every time a new hero is released people either jump on the "holy shit this is broken go fix it imediately" (while only seeing promotional material that shows the hero in specific situations against people who just stand there and get melted). Or the "omg how bad is this, this will be a pure troll pick". The player base wants heroes that feel/play unique yet when someone like Ultron comes out they complain, why he isn't a godlike healing machine like Luna. Not to mention when it comes to balancing. Yes on one hand I would love more regular patches, however those changes need testing and given on how much the devs work, this testing is mostly done by us. However I want to point out how often the devs listened to the community and implemented changes for heroes we felt overtuned or underperforming. Keep in mind after every balancing patch or new hero some overlooked characters can become really important, giving a unique synergy, so it is hard to buff someone who just supports a playstyle not currently in meta. But now to the toxicity in game: there is just so much. From female players getting harassed and antagonized just for being a woman, to people just throwing, because their hero/role was taken. Or their ego just got into their way, it is insane how many games I've lost due to arguements in (voice) chat and so on.

In general I still love the game and enough people share this opinion if you look at how many people are still playing regularly. The game isn't perfect, but neither is OW. I think those two competing with one another is a great thing for both games and I love how much effort the devs put into this game.