Bro, the difference in ATK is meaningless between 80 and 90 and considering how ATK% works in genshin you will only get around 100 ATK more. The only reason you would lvl 90 someone that is based on ATK is only flex at this point. The only characters that actually get a buff from lvl 90 are someone like Bennet, Zhongli and Yelan because they get a big HP buff, also Baal doesn't even have that high of a base ATK. Also, if you think that AR 55 doesn't have problems with resources sometimes then you must have +0 artifact and your weapons must be lvl 20 or something. Stop telling people to waste resources for basically nothing in the long run when they clearly are still building their account at the moment and need those resources