It's very obvious that these accounts were abandoned and then either bought from their original owners, or more likely bought from someone who compromised them, because of their history and karma.
And I would bet money that Reddit is well aware of this phenomenon, because not long after it became so common as to be impossible to ignore, they papered over it by allowing users to hide their history from public view. (AFAIK subreddit moderators can still see it, but typical users now have much less ability to see whether they're interacting with actual humans.)
Yeah it's become my default assumption that any user who does this is either a bot or a bad-faith troll.
0: https://wiki.roshangeorge.dev/w/Blog/2026-01-06/Is_The_Inter...
Also just repeating something from the linked article, but often with different wording and in a tone that makes it seem like it was something that the article missed.