Why isn't there, or why isn't this, sub ALL about the fair values of stocks?

seems like that's one of the very first steps in determining if a stock is attractive to a VALUE investor. is it mathematically complicated to value a share? Is it proprietary, is it behind paywalls, or is it really just subjective? if i wanted to pay some website to give me a fair value, there's no way the info they have and the equations they use are not easily available and programmable, and you could have a reddit sub where that type of thing happens... right? nope, or it would exist. so, what's so hard/subjective about getting to a fair share price?