I can provide an earnest argument, if you like. I put 400+ hours into DotA in college, and enjoy games like Valheim, Lethal Company, and Monster Hunter with friends regularly, but pretty adamantly avoid competitive anonymous multiplayer these days.

1. I dislike the increased commitment of multiplayer games. When playing with a group, I have to worry about “letting down” the group, and must play fully sweaty at all times. Learning is also much more stressful and frustrating due to the social element. Even if the group isn’t toxic, I’m more aware of my failures and their consequences.
2. There are engaging and difficult PvE games that challenge me, with good AI. Souls, Sekiro, DOOM Eternal, and Hollow Knight are all excellent examples with lots of unique and interesting challenges. I also enjoy stuff like speedrunning, which can take easy but fun games like Mario Odyssey and raise the skill ceiling infinitely.
3. Matchmaking eliminates the feeling of progression. I love the satisfaction of improving. I.E. Beating Sekiro and starting NG+ only to crush the opening areas that took hours because your skills have improved so much, travelling through an earlier area in Dark Souls and marvelling at how easy it feels now, or setting a huge new PB in a speedrun. Matchmaking with strangers eliminates these moments, because your MMR increases with your skill, trapping you at a 50-ish% win rate permanently, unless you smurf, which is short lived and kinda scummy. You may improve and hit a win streak, but will quickly be slapped back as your MMR increases. And I don’t find seeing that number climb up to be nearly as satisfying as real moments that prove your skill.
4. I enjoy some atmosphere and narrative. It’s tough to deliver a cool world via character trailers exclusively, and most multiplayer games never get an “Arcane”. A single player experience will always have some of that, and it can be awesome.
5. Pacing and variety. A good game experience is paced out with moments of calm, maybe some puzzle solving or narrative, and moments of intensity and tough fights. That stuff is good when done well. Something like DOOM Eternal gets my heart pounding like nothing else in arenas on higher difficulties, but knows to let you breathe in between, so I can enjoy that heart pounding pace for more than 30m at a time. Online games will try with something like spreading players out in a Battle Royale, but it’s not the same.
6. Also, I just like pausing, lol. If my wife needs something, it’s nice to be able to just put the game down, I don’t like being chained to my desk for 20-40 minutes depending on how the game goes because I’ll lose rank and disappoint the team.

Also, I say anonymous because a lot of these problems disappear if you play exclusively with friends. I love the Smash series, for example. You have an objective skill benchmark in the friend you’re playing with, as well as someone who’s understanding when you have to go or do something. That’s really cool, but also damn hard to schedule and not something I do often for PvP.

Competitive anonymous multiplayer is great, for those that like it. More than happy to let you enjoy that. But personally these cons outweigh the pros for me, and I’ll continue to be disappointed when something I’m excited for turns out to be competitive anonymous PvP.