They are, but so are digits in fiat bank accounts. Really they are just another fiat payment routing clearinghouse. They work better than SWIFT but slower and irreversible.

I think they are mainly there and continuing to do well due to being an easy pathway between fiat units and satoshis, riding on Bitcoin's value, which more or less proportionally tracks with the amount they have circulating, give or take.

If nothing else, it brings people into two more clicks to stacking sats. Of course they are irrelevant under a bitcoin standard since nobody's using that trash anymore but for the time being, it's got its benefits and it impedes our enemies more than it does to our cause. They are the gateway drug from forex to bitcoin.