There is a user preference to disable selection quote, which was put there for the (bizarre, IMO) users who reflexively select text as they read. I was quite surprised to hear about this because it seems… unhinged to me … but a lot of people apparently do this and pushed for it at some length in 2013 when we launched? 
That’s why we have “Enable quote reply for highlighted text” under the interface section of your preferences.
Beyond that, enforcing “no quoting of other posts, ever” would need to be a plugin, I’d think. And clever users would be able to get around it in a multitude of ways, sort of the same way users can generate blank posts if they reaaaallllly want to, though we do try to strongly discourage it.