I entirely agree and I highly recommend that most instances generally ban bots like this.
But I'm not against people running them on instances where it is specifically welcomed, and I think other instances shouldn't defederate the instances that do - we should just ban the bots and/or the remove the communities that consist entirely of bot posts.
This way, any users who want to use a lemmy client (or website) to read a combined view of the lemmyverse-at-large plus some scraped subset of reddit can just make an account on one of the servers that is doing that.
Human users of those instances should be able to participate in the larger lemmyverse, even if the bots are banned from the rest.
I don't see it in the modlog now, but I think it was me that banned @bot@lemmit.online from lemmy.ml a few months ago, and I just banned a similar one @Dannebot@leddit.danmark.party today (and sent basically the above suggestion to the operator of it).