From my experience it's the channels that don't have a lot of active members, maybe like 10 or 20 people logged in at all times. The value of conversation is increased majorly in those channels.

Asking for mentoring and asking someone to do your homework are two different things. There's always been and there always will be freshmen who attempt to short cut their way through classes by trying to make someone else do solve their homework. It is and should be frowned upon.

Politely asking smart questions about how to progress in your homework, on the other hand, is just fine.