> If there isn't enough usage of a feature to justify prioritizing engineering hours to it instead of other features, so it's removed, that's just a regular business-as-usual decision. Nothing "political" about it. It's straightforward cost-benefit.

Then why is Google actively shoving multiple hardware APIs into the browser (against the objection of other vendors) if their usage is 10x less than that of XSLT?

They have no trouble finding the resource to develop and maintain those

You have to keep developing new things to see what proves useful in the long-run.

When you have something that's been around for a long time and still shows virtually no usage, it's fine to pull the plug. It's a kind of evolution. You can kill things that are proven to be unpopular, while building things and giving them the time to see if they become popular.

That's what product feature iteration is.

WebSerial and WebUSB are the best thing to happen to browsers since sliced bread. Just because you can't see why it's amazing that users won't need to give some random, badly supported driver SYSTEM/root privileges to run their specialized hardware -- encompassing hobbyist, educational and professional uses -- doesn't mean it's not obviously useful, and Mozilla's stance on keeping it out of Firefox will just harm their market share in these area -- education probably being the most hurtful.

From what I gather here, XSLT's functionality OTOH is easily replaced, and unlike the useful hardware support you're raging against, is a behemoth to support.