> people would trust rumour less, not form mobs more

I believe you are right. When the first unbelievable clips appeared on Facebook (where the most gullible people are), you could see the old ladies cheering "oh how wonderful! where did you film that?" Now in the comments section you will mostly see people saying "sheesh, stop polluting my feed with these fake AI-generated spam". Don't get me wrong, many people still fall for them, but the tendency seems clear - after all, we managed to survive because of learning.