Exactly- the teams would all work out an optimum desired start/finish position in any such races and/or you might end up with a ridiculous situation with everyone trying to come 7th or 8th or some such rubbish.
Mostly you'll just get a big train of cars and probably a load of crashes with lots of the midfield trying ambitious moves to get to the front of the grid and the drivers at the front with no WDC ambitions really desperate to keep their position. How long is the race? How possible will it even be going from near the back to near the front? Are the top cars really going to risk crashing out and starting last in the main race? They'll be super cautious.You'd probably get the AT cars and RBR #2 car letting RBR #1 straight past while actively holding up Ferrari and Mercedes, and probably the same with some other team combinations.
It's one of those that looks good on paper or in someone's mind but the reality will likely cause more issues than it solves.