Rollback hasn’t been in fighting games for very long at all. It’s a relatively recent addition to the genre, and has resulted in dramatically improved online play. It’s still new enough that it’s even touted as a feature & selling point in marketing. Within the fighting game community, online play/tournaments have typically been regarded as a joke & not representative of skill at all because delay-based networking woes. However nowadays, with rollback, online tournaments are held regularly, more accessible than ever, and regarded more highly than before. Rollback is greatly helping the genre stay alive.