If you're going to have a centralized system, and your proof-of-work is going to be meaningless, then why bother with a blockchain at all?
Just store the user balances in a traditional database. It will be faster, easier, and cheaper.
Blockchain exists for purposes where a traditional database is insufficient (distributed trustless systems).
Exactly
Sometimes people choose a solution and try to find a problem that fit that solution.
But it is the other way around
Although blockchain is a buzzword now , it doesn't fit every company database needs.
Blockchain is a slow and expensive database. It is necessary for very specific situations where you need a trustless environment. A centralized database doesn't need it.