Critics of Android embraced a meme that Lollipop was Android's Vista, substantiated by users anecdotal claims about poor battery life from a given upgrade, or the changes to notification levels, etc. So you still see the echos of that. I've never seen someone go so over the top to claim that it justified vendor skins, though, so this is a new pinnacle.
Yeah, the ritual of rebooting the device every two days because of the memory leaks and camera crashes were quite an incremental update over stable Kitkat.
Even ignoring the placebo effect, and a contingent of people carrying forth a message between advocating the amazing world of task killers, what in the world would a skin have to do with that? TouchWiz and others are literally layered over stock Android, so if there was a fundamental issue it would have the same issue. The notion that the skins are somehow superior is nonsensical, despite the comical, ignorance-induced downvotes I've predictably received.
To everyone else it was an incremental update.