As much as not increasing your level helps with stuff like sage, for every level you gain, you gain more BP as well.
No matter how much he pushes for the top of sage with his level, he will eventually get beaten out by others who have a higher BP and didn't grind as much as he did.
I agree with separating by BP, because I'm tired of seeing 90k bps in my field lol, but what does Oas do with them then? Any suggestions for that will be good too.