Yes it's decentralized and very hard to stop to parties from making a crypto transaction. But what about cases where you need to convert your crypto to say euros because the person/business you need to pay doesn't accept crypto? Don't you need an exchange for that?

How easy/ widely accepted is it to pay for things using crypto (gas, rent, mortgage etc.)?

The point I was trying to make is that if paying for stuff in crypto isn't ubiquitous, it's far less practical as a form of currency.