Yeah, but they shouldn't be waiting for someone to defeat a block before they help. The idea is to go double someone if you don't have anyone to block... at least that's how my coaches taught. If my highschool OL coach saw someone standing around like that on film, they'd be doing machine gun drills the next practice. My coach wanted you hitting someone, even it was just a punch to help the initial blocker control the defender.
From what I've seen in the NFL, linemen never stand around. Even on a 3-man rush, everyone is blocking someone.
I don't think this is one of the things over criticized. I've seen lineman standing around like that while the QB took a sack. They don't go to help until it's too late, if at all. The blocking AI has been pretty bad in the past. They have a long way to go if this is supposed to look like what we see on Sundays.
Maybe folks won't feel the need to drop back 20 yards if they could trust all of their linemen to block someone.