Boba Fett was a big believer in the EE-3 ... ultra-strong netting that even a rancor would struggle to shred. Not a weapon per se, but a great place to stash a big ol' concussion missile and ...

It seems more likely that the Empire simply stopped enforcing the existing galactic laws, and that bounty hunters like Boba Fett seized the opportunity to add a new weapon to their arsenal.