However USATT has made this confusing by introducing a separate ranking system like ITTF
IMO these are fake & pretentious because on the USATT rating system it is like as you said, the rankings are like the inverse of the rating (Higher your rating, lower your ranking number & vice versa)
But unless i am mistaken, the difference is that the new ranking system is more like a participation award I think. You get points for participating and winning matches & no penalty for losing.
My understanding is that the ranking system is more like from bridge where the more you just play, the more your ranking will be as long as you keep winning matches without worrying about losses. If I am not mistaken ITTF rakings are somewhat like this.
USATT has said that they will keep both systems but we will see.