They're completely relevant. There's a finite amount of resources. You have to decide where to spend them. GL hasn't had a standard for error messages for 22 years yet somehow it's doing just fine so this certainly doesn't seem like a priority for resources.
Epic, Id, Crtek, Autodesk, etc haven't been clamoring for this feature in OpenGL so why is it needed in WebGL?
And again, YOU'RE THE ONE HALF-ASSiNG IT! You're asking for 13+ teams to waste time on this when you could probably solve your specific issue with 5 lines of JS regexes
Great way to spend resources dude!