It's pretty simple, nowadays the ONLY way to have fun in most multiplayer games is to win by any means. Outside of a few games like minecraft, every other game is designed around winning. 6 of the most played games on steam right now are some combination of competitive FPS / pvp survival or Dota 2. All of these games give you way more rewards for winning over just casually playing so over time the community is incentivized towards maximizing ELO, mastering the meta, and finding any ways to gain an edge on the competition.

I won't say it was better back in the 90s/ early 2000s but games had lobbies and people would just naturally drift around until they found one that satisfied their needs, be it playing more causally or for a more hardcore experience. Nowadays matchmaking is all controlled by the almighty algorithm which is just a glorified ELO/MMR system and dumps people together regardless of whether or not the game is "fun" for them. Worse yet "Quitting" is actively punished so you just have to stay in the game being frustrated and angry at your teammates until you lose. I always use pick up basketball as an example of how lobbies should work with people being given the choice of playing until they are tired/bored and punish trolls by excluding them forcing them to seek out another court or just start their own games.

Now that i have sworn off all competitive multiplayer games because i used to be a real fiend with several thousand hours in Dota 2 i have come to realize that as fun as the game is the fundamental failure of every matchmaking system is that your fun will always be dictated by how often you win because that's the only thing that is rewarded both in the game and by the community. If you look at any forum for these competitive games it's always the same complaints with people bemoaning that the balances is bad (AKA i don't win because if i did why would i complain), the game is too hard for newbies (AKA i don't win because the skill level is too high), and that the community is too toxic (AKA i don't win because i don't take the game too seriously and people get mad at me).

I'm much happier playing singleplayer games or exclusively cooperative games like Helldivers and Deep Rock Galactic and think most people would be too but they need to come to the realization that it's not the games fault per se but the underlying mechanics behind the matchmaking systems.