The benefits to merging the stats don't really seem like they outweigh the work involved on the dev's end, tho. Like. None of the arguments for it are really so convincing that they should change what they're doing. At worst, it's a minor inconvenience.

Not to go all slippery slope, but I'mma slippery slope here.

Why have STR/DEX/INT/MND when everything could just be "attack"?
Why have Crit/Det/DH when it could just be "extra attack"?
Why have the extra damage stats at all when they could be rolled into the base stat?
Why have the speed stats at all when you could roll the variance into base attack?



To a certain extent, some/much of this is simply designed to give the illusion of complexity. Sometimes it's just not very wise to look under the hood and break that illusion.