Quote from EagleDelta2
No, it's not the responsibility of the consumer, but you can't have a game where the devs are responsible for supporting mods AND prevents users from cheating - one or the other and even then usually 1st parties don't provide anti-cheat. On PC it's usually done through punkbuster, on consoles, it's Sony, MS, or Nintendo that are responsible for their networks. End of story there.
As for FPS bugs - that will always be a debate. I don't have any FPS problems and when I do, through my own troubleshooting, I find it's because the graphical settings are higher than they should be for my laptop's hardware. It's the devs job to make a game, not their job to make a game that works on every PC between the years 2000 and 2010.
ANY game with active updates always warns that the new content/features/updates could render the game useless on older computers. I don't expect it to be any different with Minecraft.
So what, exactly, does that have to do with bugs?
For instance the duplication bug, which is something you can just not do in singleplayer but could also screw up the balance on a multiplayer server than an admin has worked very hard to achieve.
Or how about the fact that the enderdragon fight is still bugged in SMP?
Then there's also a slew of bugs that aren't specific to multiplayer.