Can you explain how it is centralized? Because… it isn’t.
No typical business is going to work with BTC addresses on the raw. They're going to (and currently) using simple APIs like Coinbase API (https://developers.coinbase.com/) to "implement BTC receipts".
As far as US business is concerned, the typical payment processor for bitcoin is Coinbase. They handle the bitcoint transfer, transaction history, and conversion into USD all at the same time.
Bitcoin works the way it is intended, that is peer to peer payments. Everything else is just ecosystem, which can be replaced. Coinbase is important as an on-ramp for users for now, yes, but their importance to the network is peripheral.
There's your theory, and there's the practice of the internet and business. In theory, they should be the same. In practice, they're different.
I’m talking about Bitcoin, and you better believe I run a fullnode. No provider required. I recommend you run a Bitcoin full Node too, and transact without any 3rd parties!
The users/miners decided, in decentralized fashion by contributing resources. Decentralized!