Cellard was a great member of this forum, I'm not certain if he was promoting any of the project. Another user bill gator is too banned till 2021, he was promoting Chipmixer. These are only signature ban.
The question is, how come dudes with an outstanding reputation like them did plagiarism?
About the signature campaign, I think this mass ban only remove a small percentage of participants. I doubt it will affect the forum's dynamic since managers could quickly get new campaign participants.