While I come from more of the Rust sort of side of things, and I agree with you that I'd rather have widely-used languages having static typing (though I've written more Python than Rust), it's also true that different languages have different degrees of uptake in different areas.

As things stand, Piefed, Lemmy, and Mbin all have an integrated Web frontend and backend, with third party client support via API. That is, they work kind of like Reddit does, not Usenet or IRC servers, where the backends and the frontends are entirely different projects.

I'm confident that Python has vastly more uptake for frontend Web development than Rust does. That means that it's going to be way easier to find contributors who understand how to build a Web UI who know Python than who know Rust.

If there were a split from this approach

that is, if the UI became decoupled from the backends, and users just used Aphrodite or mlym or whatever, and the backend wound up looking something like Usenet server software,

then I think that there might be a stronger argument for doing the backend in something like Rust, depending upon how it was structured.

But I think that Rust probably creates a high bar for attracting front-end contributors who are knowledgeable in building Web systems.

I'd also point out that Reddit started out in Common Lisp

Paul Graham, who was involved with its early days, is a huge fan of Common Lisp

but eventually was rewritten in Python.

EDIT: There's also Sublinks, in Java, but it doesn't look like it's getting a lot of activity.