WIT should have the same expressivity power as the component model

My mental model has been that WIT is "just" syntax sugar[^0] on top of the component model: anything expressible in a raw component model interface should also be expressible in WIT.

[^0]: Curly brackets instead of S-expressions, stuff that helps bindings generators but don't affect semantics like doc comments, a package system to spread definitions across files, etc...

But this is not actually the case today. I strongly believe it should be.

The biggest counterexample I am aware of is https://github.com/WebAssembly/component-model/issues/287.

My hopes in filing this issue are two-fold:

1. Build consensus that "anything expressible in a raw component model interface should also be expressible in WIT" is a highly-desirable property. Does anyone disagree? Can we formalize this into one of the design docs in this repo or something?

2. We can do a collective survey/audit of CM features and exhaustively enumerate WIT's expressivity gaps. Is anyone aware of any other counterexamples?

Start with the counterexample in WebAssembly/component-model#287, then review the repository's design documents and the component model features they describe. Done means reaching consensus on whether WIT should match raw component-model expressivity, formalizing that property, and enumerating the remaining WIT expressivity gaps.