The utilitarian argument here invalidates this premise of the pins needing to be human, which is what is interesting. If you are getting utility out of it and you didn't know it was a bot, you are actually still better off.
Having said that, you do make a very good point.
If a bot could find things I like, and put it in a sensible pinboard, then I'd probably follow it.
I don't care about Pinboard skimlinking any affiliate links, even ones I'm using. (another post in this thread explained how bots would avoid that limitation with redirects.)
I do mind, a little bit, if a bot owner is making hundreds of dollars a day by manipulating flaws in Pinterest, because arms-racing could make Pinterest much less useful.