Yes that's pretty much the extent of the reasoning and I don't see what's wrong with that.

Bitcoin on a centralized exchange cannot be traded for goods and services until explicitly withdrawn, unlike most brokerage accounts where cash is cash and many will even give you a debit card so you can spend directly from the account. This strongly decouples bitcoin and most other cryptos from the total money supply.

When you're on Binance and you send them one BTC as a block chain transaction, you are receiving one Binance!BTC that does not exist outside of that walled garden.