This trope is very common due to the numerous storytelling considerations fueling it. Drama thrives off of conflict, and having the few put up a fight against the many is basically a free conflict coupon that's automatically viable during any few vs. many confrontation. Why have the superhero team curb stomp the villain if you can make him powerful enough to force them into Teeth-Clenched Teamwork? Why have the dozens of Mooks club The Hero unconscious three seconds into an encounter if you can let him take down seven or eight of them before he collapses, to show how much of a Badass he is? That would be letting some perfectly good dramatic tension go to waste.