Why would Bitcoin purists care about off ramping onto fiat?
This seems awkwardly unnecessary for a technology that has only prioritized deflationary economics and economic sovereignty through private key encryption.
Serious answer: Because they have to eat. Being a purist doesn't mean they can afford to ignore the world they live in; even if they believe that USD is fundamentally worthless and keep all their wealth in Bitcoin, they still need to occasionally pay bills to people who don't take Bitcoin.