While I haven't played online mutiplayer in years, I have a great deal of respect for the concept.
I don't. Having human opponents inherently limits what you can do to a significant degree. This is especially important when building challenges. The difficulty curve and encounter design of a good singleplayer game is impossible in a multiplayer framework. While multiplayer gaming can be fun, it inherently lacks depth specifically because it has to cater to feeble humans with limited playtimes and has to be inherently fair for everyone involved. This usually means that it's either a round-based game where consequences only last for 30 minutes or so and all the mechanics have to be simple and available quickly, or they are long-term RPG type games which can't have real consequences (like taking over of regions) because all players have to be on a level footing (which is why World of Warcraft and most other MMOs feel so incredibly stale to play, since your choices are meaningless).
As a result, even the best multiplayer games usually boil down to relatively straightforward and uninteresting gameplay. Even if it's implemented well and requires a lot of skill, more often than not it's just not really that complex or interesting, and it can never be.
Even the most complex and well-made MMOs are still constrained by these limitations. Which is why even the good ones feel so bland to play after a while.
I have had a lot of fun playing Multiplayer games in the past, and I don't want to make it sound like I'm shitting on them or saying they offer nothing of value or are completely worthless and unfun. It's definitely fun to have a good romp with friends, whether it's in an FPS or something like Age of Empires 2. But at the end of the day, multiplayer games will never hold my interest and attention (or make me think and strategize) like a singleplayer game can. Multiplayer games are just inherently incapable of offering that interesting of an experience.
It's funny, the accepted truism of "if you want a real challenge, try versing another human" isn't really accurate. It's true that other humans will always offer a more dynamic experience compared to a computer, and a human that's significantly better than you will be very hard to defeat. But there's no real challenge there. Nothing to overcome. Usually it's either you pwn someone because they are shit, or they pwn you because you are shit, and there's not much you can really do about it or learn from it.
Completing Dark Souls and fully exploring that world was a far more challenging and rewarding experience than I have had in any multiplayer game, and I have played CS:GO at global elite level.
Just one of many highlights of gaming in the 90s was that singleplayer was king. Multiplayer was always the secondary mode.
Ehh, not really. A lot of the big first person shooters were MP focused. Quake 3 and Unreal Tournament come to mind, and they absolutely took the world by storm.
the 1990s was the era of the arena shooter (Quake, Counter Strike, HLDM, Tribes etc)
The 2000s was the era of the asymmetrical and complex team shooter (Battlefield 2, Wolf:ET, etc) and the MMO (world of warcraft specifically)
The 2010 was when things really got cancerous and we got MOBAs and Hero shooters everywhere.
Every period in gaming for the last 30-40 years has had a large multiplayer focus.
I agree that MP is much more focused on now than it was in the 1990s, though.