I would think that they need to set a somewhat permissive threshold to avoid too many false positives due to people sharing a network. For example, a professor may share a reddit post in a class with 600 students with their laptops connected to the same WiFi. Or several people sharing an airport's WiFi could be looking at /r/all and upvoting the top posts.

I think 8 accounts liking the same post every few days wouldn't be enough to trigger an alarm. But maybe it is, I haven't tried this.

I had one main account but also a couple for using when I didn't want to mix my "private" life up with other things. I don't even know if it's not allowed in the TOS?

Anyway, I stupidly made a Valmond account on several Lemmy instances before I got the hang of it, and when (if!) my server will one day function I'll make an account there so ...

I guess it might be like in the old forum days, you have a respectable account and another if you wanted to ask a stupid question etc. admin would see (if they cared) but not the ordinary users.