I have seen no declarative proof that companions can be reset to level 0. Meanwhile the drama over removing multiclass restrictions is overblown as well. Point buy systems could have been replaced with dice roll and allowed Uber builds. By default if you mutliclass into a class with a low base score you will perform poorly. It's a built in check and balance.

I go back to the original DnD ( 1st edition) and we must remember TTRPG and CRPG cannot function identically. Since it's a single player/Co Op experience, I think some flexibility is warranted.
Rules as intended from 1st edition forward are at the discretion of the DM.
Game looks amazing
Enjoy it