This is may get some disagreements, but I'm not particularly crazy about online gaming/multiplayer for various reasons.

1. Focusing more on multiplayer modes as opposed to single player. This especially applies to FPS games like Call of Duty and Battlefield. It's like people care more about the multiplayer/zombies modes than the Campaign. And I'm like the complete opposite. I even think games like Overwatch and Rainbow Six: Siege could've worked better if they had a single-player campaign.

2. Player behavior and toxicity. I'm very certain than everybody who's played at least one online match or session has come across one rude or obnoxious player. It happened to me one time, when I was playing a little bit of the multiplayer in Watch Dogs and it was a somewhat empty server, few players, and I could hear one person in the chat being frustrated and swearing profusely. He wasn't yelling or screaming, but he was a little agitated and I honestly can't remember why. Not the worst case, but still.

3. Feeling insignificance (sorry if that sounds deep). The best way for me to explain this is when you first jump in into an online game, you feel like a nobody. A perfect example is when I joined one of those modded GTA FiveM servers and I was completely lost. I was dropped into an isolated part of the map, near a gas station, and I was looking for a vehicle, didn't matter what it was. Problem was, there was NO traffic spawning where I was, and so I asked the chat where I could find one. They never replied back. At that, I just gave up. If anybody here owns a copy of GTA 5 on PC, my advice to you would be to install some mods, especially those that bring online-exclusive content to the single player mode.

Sorry if this sounds rude. I do understand why people play online, to meet new people, teamwork etc.