The best part of the fediverse is that anyone can run their own server. The downside of this is that anyone can easily create hordes of fake accounts, as I will now demonstrate.
Fighting fake accounts is hard and most implementations do not currently have an effective way of filtering out fake accounts. I’m sure that the developers will step in if this becomes a bigger problem. Until then, remember that votes are just a number.
I don’t know how you got away with that to be honest. Reddit has fairly good protection from that behaviour. If you up vote something from the same IP with different accounts reasonably close together there’s a warning. Do it again there’s a ban.
I did it two or three times with 3-5 accounts (never all 8). I also used to ask my friends (N=~8) to upvote stuff too (yes, I was pathetic) and I wasn’t warned/banned. This was five-six years ago.