It's not a fair statement to say that UAs don't care about shader
compilation issues. On the contrary, many of the tests in the WebGL
conformance suite came from developers who ran into shader compilation
or evaluation problems on one platform or another. Wherever possible,
workarounds have been added to implementations, and these reports have
often resulted in bug fixes to the graphics drivers.
It is impossible for the browser to detect all shader compilation and
execution problems ahead of time, but where it can, we will try to.