Personally, I think these one-liners may be for a different reason.
If I stand back, and try to view them with no preconception, they look like people are trying to participate in the conversation. Many of the people probably don't speak English as a first language, and that accounts for some of the apparent inappropriateness. But it's always awkward, trying to join a conversation with people you don't know and it's easy to step on toes and put your foot into your mouth, if you don't know the ropes.
Quite possibly, some of the motivation for joining the discussion is google analytics, or other transparent/hidden online rating systems. Who knows. For whatever reason, they want to join the discussion. After all, this is a discussion board. I know the community team wants to encourage participation, for their own reasons, because the boards have to demonstrate statistical and financial benefits, to justify the effort and expense of maintaining them. Most of the posters here would probably prefer to have productive participation, that contributes to the discussion in a more meaningful way. But people have to learn to walk by taking baby steps.
As to where the odd non-sequiturs are coming from ... most of them are copied and pasted from other replies. Sometimes, it's another reply earlier in the same thread, but that's rather obvious, and it may result in moderator action sometimes. So, they may be learning to copy replies from other threads. It's inevitable that these non-sequiturs may sometimes be inappropriate. To my mind, that's a clear indication that there is probably a language barrier contributing to this.
I'm not trying to justify these non-sequiturs. They're really a kind of spam. But I find that if I can understand the motivation, it helps me to be patient, and hopefully try to help them learn to participate more productively. Even if it was just to focus on real questions, that can lead to helpful answers.
