WASM does appear to have significant tailcall consideration: https://github.com/WebAssembly/tail-call/blob/main/proposals...

the high bit here seems to be 'Currently, the Wasm design explicitly forbids tail call optimisations'?

I'm not keeping up closely with WASM development, but doesn't it say this was the case at the time the proposal was written? It seems it goes quite extensively into the subject which is a good look for WASM (which I'm otherwise on the fence about when it comes to using it outside of browser scenarios).