Comment by hedgehog

Something compiled to WASM still gives a fair amount of control over memory layout, something that AFAIK is not possible in JS without building effectively a new embedded language on top of an array (Emscripten being an existence proof that you can do more or less anything that way).

One place where an interpreter + JIT language could be interesting is if it were sufficiently safe to allow user code into the query execution engine, such that the JIT could optimize it all together.