From the latest spec [1]:
> The specification reached an impasse: all interested implementors have used the same SQL backend (Sqlite), but we need multiple independent implementations to proceed along a standardisation path.
[1]: https://www.w3.org/TR/webdatabase/
This won't be a problem for wasm SQLite because it isn't a standard being shipped by browsers, just another dependency.
The standardization issues around SQL already exist, are already widely known, and where common workarounds are already in practice. It's also an open source project that could have _easily_ incorporated compatibility code for this specific use case anyways.
They made blind fealty to process more important than the outcome to end users.
What a waste.
As I pointed out in a separate comment:
Richard Hipp committed to creating and maintaining a flag in SQLite that would force SQLite to use whatever subset of SQL the WebSQL people settled on for their API. That would have of course worked independently of the SQLite version. (He also offered to write the SQL part of the spec.)
https://news.ycombinator.com/item?id=41860067
It was such a lost opportunity. I'm sure the SQLite guys would still be happy to do the work, but there certainly isn't any momentum on the browser side anymore.