To be discussed. The system could show who marked the user as spammer. And there could be an option for others to unmark him if they disagree or if the post quality improved.
How can we prevent system misuse?(keep hiding some signature).
Then there could be a formula to decide whether or not to remove the signature rights
Remember we do not have a clear definition of spam.
generally, I agree with you. this is the best solution because signatures are the main reason for the spammers.
I do not know if theymos will agree with you because he already make
Serious discussion section