One of the things that's well understood about SQL is that interop is terrible. No one expects to write anything substantial using Postgres and be able to port

One of the things that's well understood about SQL is that interop is terrible. No one expects to write anything substantial using Postgres and be able to port it over to MySQL or MSSQL without a serious amount of effort. On the backend, that's more or less OK, although one of the value propositions of ORMs is that they make it somewhat easier to change databases later by reducing the amount of product-specific SQL that has to be rewritten. On the web, however, it's totally unacceptable. Sites are expected to keep working between multiple browsers and across multiple browser versions. To achieve that level of interop would have required someone to sit down and write a detailed specification of the dialect of SQL that should be supported on the web, and for browser vendors to take the time to implement it. In practice people weren't willing to spend the time doing either of those things; the level of buy-in was enough to fork sqlite but no higher. Eventually the web might get something like WebSQL. But the way it will happen will be for people to implement SQL in js on top of IndexedDB. If that proves popular but has issues (e.g. with performance) then there will be renewed impetus to do a proper job of a WebSQL specification.