skeptics love these 'debunk' style questions 
but they're almost always asking the wrong question:

>why does it need a token/chain?
- it's not a 'need' question
- *can* it have a token/chain?

>why can't agents use stripe API over crypto?
- it's not a 'can' question
- *would* they use stripe over crypto?

May be the same reason the skeptic had MySpace Account, then Facebook account, then Instagram Account and then Youtube Account.

"you can", and may be there is more positivity on the other side. Try it !