I'm sorry, I am not a high-rated player by no means, BUT I've played a lot and I was among the 16 2022 FFA World Championship semi-finalists, AND I've played with strictly all stars many times already. I definitely find the discussion above rather irrelevant because the set-up is only relevant for the 6-10 first moves. Then it's strictly the same thing.
I believe that some of the positions above are inspired by the fact that many high-rated players PREFER the old set-up as they accumulated a lot of experience and theory insight on it and are more used to that and simply like it more. BUT it's a matter of fact that for instance Radon (one of the biggest OS funs) could reach the top 20 in something like 30-40 games only with an ALT account (from 1500 to 3000) with the new standard. I think this demonstration was quite convincing and brilliant of the point I made above.
it is a conspiracy theory, but I still agree with @Arjun1516.
There should be 3 different leaderboards, as it is 3 different games.
Have you played enough standard to realize that this isn't viable?
If we restarted everyone at 1500, we would have a really fun time with high rated players at low ratings destroying everyone and making new players really confused; this isn't like standard chess and 960, it's the application of extremely similar skills to an even higher degree.
Now, if we just copied ratings, then what we'd see is players sitting on a rating and the situation being made even more confusing as is once we look at how many rating categories for standard 4PC there already are. When you ask someone what their rating is, I'm pretty sure what the response back is shouldn't be "2800 in BY Setup Teams 4P Giveaway", which makes no coherent sense to any average player not in the community.