Alright, I'll give them that. However, I think this will, like it has with the rest of the web, lead to differences in how each browser handles the spec, various browser-specific extensions, etc. In that way, it's actually worse than having one company behind it.

Wasm is the first major thing I can remember all the browsers agreeing on in a very long time, or ever.

Agreeing of course, after trying to do it on their own and then realizing they were thinking a lot of the same things.

>Wasm is the first major thing I can remember all the browsers agreeing on in a very long time, or ever.

Uh, flexbox, grid, fetch, service workers, even shadow DOM...? The cooperation between browser vendors has been exceptional over the last five years.

Are any of those as large and potentially as broad as wasm?

For frontend devs, sure.

The JS community currently deals with this by way of "polyfills" I wonder will such an approach be easier or harder with WASM ...

Any differing behaviour from the spec is supposed to be behind feature flags so that WASM Applications can reliably detect and use these.