As others are saying here, the real work lies in the underlying database system rather than the actual back-end. Yes Rust is a good system language, but that didn’t stop Lemmy from having a memory leak, and Python is also good(-ish), at least enough to make it happen. Possibly not as well at larger scales… but with subscribership falling rather than rising across the Threadiverse, that’s not really a major concern at the moment.

Especially compared to features that will attract those new people, and thereby content, if such people did end up coming.