It would never occur to me that the line is for people who need to be escorted vs people who already know where their table is. If I see a line going into the dining room, I just assume it's for everyone and wait on the line, even if I know where I'm going (although I will tell the crew an escort isn't needed so they're available to help the next person). I'll have to see whether I want to change my behavior going forward. Most of my cruises have been on Carnival, though, where the line has sort of doubled up at the double doors to the dining room allowing crew to escort from both sides. It might be tough to move ahead of the line in that situation.
I do wonder if a lot of people on the line see people skipping the line, will they just go in and wander around looking for their tables, causing more confusion and delay?