That time period in the months in and around October 2017 were effin' awful for the forum.  I recall that when I was doing a lot of reporting of shitposts (to soothe my nerves) and trying to link alt accounts, I kept seeing that many of them had registered right around that time.  I think the later months of 2017 were when a lot of ICO bounties were being created, and it brought out all the shitposters who no doubt created at least several alt accounts each. 

It was also when bitcoin was exploding in price, so it was extremely hard to find a spot in a regular bitcoin-paying signature campaign.  Anyway, that's why I think there were so many accounts registered between the summer and tail end of 2017.

I don't know a lot about what that "evil fee" is, though I've certainly heard of it.  That's for when you get IP banned, is it not?  Well, in any case it also doesn't shock me that there's a lot of "evil" accounts generated in 2017.  And boy, the numbers have stayed quite low ever since the merit system kicked off, eh?