I'd be very much opposed to that personally, and I tend to hover around the 30-35k DR range. I think it would make the entire matchmaking system worthless and undermine the long-term progression that many people have put in to slowly improving their season rankings over time. Why bother having a hard-fought race in an A+ lobby when you can tank your rating in dailies, skip all the effort and absolutely annihilate a D lobby for the same reward?
Using yesterday's race as an example, the winner in my ~35k lobby finished the race in 27:46 and he/she had clean air the whole way. In one of the top-split races yesterday, the winner finished in 27:14. 27:46 would have barely made P19 in the top-split race.
I've seen plenty of high B/low A FIA races where the winner was practically determined outright before qualifying even began because someone from A+/high A decided to sign up whilst recovering from a DR reset. Unless someone takes them out in sector 1 they're practically unstoppable and they just steal the opportunity for a win from everyone else since they don't belong at that skill level. That would become so much more common across all the D-A lobbies if there's no downside to joining races with people who can't compete with you.