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.
Not everyone starts out with an outstanding reputation. Some people obviously made a silly mistake a long time ago and some people can change their ways and become a productive member of the community. You could compare it to stealing a chocolate bar when you were a kid. Does that make you a thief for life and should it follow you around forever? Well if you keep on stealing then sure, but for others who change their ways and learn from their mistakes should be given a second chance.
For some of these old timers that are getting banned I wonder if these people have bought these accounts that were farmed via spamming/copy and pasting? I doubt someone would forget that they've done this in the past, or maybe they're just playing dumb. It's very surprising how many users have done it and even more so for how long they got away with it.