Well, they have "reasons" in that not resetting rank make it easier to get to six path in the coming season (eventually).

But it doesn't work in practice because your actual ranking pts, which is what matters, is not set to reflect your rank, which makes it pretty moot as people could have very low pts, or even negative pts regardless of whatever rank they might be in, so it's entirely useless.

I mean it could work for an extreme minority of player who actually manage a net gain of rank pt every season (but not enough to get to six path in one or few season). But... like I said, extreme minority.