you're quite correct, and the network I've been able to identify is not the only one, albeit, hopefully a particularly large one.

The pattern you correctly describe can be seen in numerous smaller operations. That's why it's so important to get AI recognition on this like @sadkitten is attempting.

More importantly though, the guys at the steemit HQ need to work on the account verification, essentially they are sponsoring operations like these by not vetting their signups properly!