Then you would have to think twice about the company you may be giving money to (ie the stock market and private bank loans). That's the whole objective of this. Every company is going to need an accountant in one way or another and you don't really need to follow strict GAAP for management requirements (what else is EBIDTA for if anything?), but it's something completely different than saying: I made x dollars and spent y dollars, here is what I have and what I owe, please give me money.

At the end of the day it is a question of convenience/standards, if GAAP didn't exist maybe firms could use a modified accrual standard that is wholly compliant with tax reporting and that's it.