My impression from when I’ve encountered this is that it is an attempt to repel bots.

hmm bots don't use keyboard or mouse copy & paste so I don't see how that makes sense?

my impression is this is just stupid product managers who don't understand why it's a bad idea to force all your users to manually type out their passwords or email addresses just because of the 0.1% of people who would copy and paste one with an error in.