You already could do this in TTYD for all realistic purposes.
I put my first level in FP, then every single level after that into BP except one level each in HP/FP around the start of chapter 4, and one more for each at the start of chapter 7.
I finished the Pit of 100 Trials with 20/20/84 as my stats (did not grind levels at any point in the game, but beat it post-game) and found it absurdly easy--only took damage on Mario two times going down, and one was when I tattled an Amazee Dayzee since I didn't see any in chapter 4 while I still had Goombella. Used nothing but Point Swaps for infinite FP/easy peril on partners and one Life Shroom for that Amazee.
"That is why war is so tragic. To win means to make victims of your opponents and give birth to hatred." - Kratos Aurion, Tales of Symphonia
Yeah, it was confusing for me because I had never played PM64, only PMTTYD, where that system is actually put into place more or less. I mean, you could be a level 30 with 10 HP 5 FP and 99 BP or whatever.