Cryptocurrency Value Added

Hi All,
Great forum as ever - thank you to those that made it possible,

I am learning about the crypto world and blockchain etc …
How does a centralised (un-mined) cryptocoin/currency add value to a private co?
Let’s say an Uber-like startup decided to “issue” cryptocoins as incentives to attract
punters - am not clear if that add value or not?
from a practical point of view how many coins could they issue?
is there a formula that govern issuing the coins?
… so many questions …

thanks and keep up the good work