That's the whole point – most of those things aren't needed for cryptocurrency because cryptocurrency is trustless. You pay for gas in the same currency you get paid in – crypto. There is nobody to call to cancel my credit card because some 3rd party does not control my credit card – I do. Ditto for "managing my account".

If I want to convert ETH to BAT or whatever, I just authenticate (using the same wallet as used above) to a thin wrapper around the network and everything happens on the Ethereum network itself. Meanwhile, if I want to convert USD to GBP, the layers below whatever service I actually use (let's say TransferWise) as the consumer is deeply nested, probably involving somewhere between 5 - 10 different entities.