Comment by no_wizard

>Are any of the examples you gave an open standard with multiple implementations from different companies?

ECMAScript / JavaScript. It has evolved at a faster pace since the introduction of ES6, and we been getting new features every year for awhile now. Given the types of features they're willing to ship with the languag and that many of the same people working on the HTML spec work on ECMAScript, it seems 'niche' isn't an issue (simply look at how many features have been added specifically only for classes vs the amount that the language construct of class is actually used. Its tiny in usage, but they've added alot of class specific features)

Other notable examples include the C and C++ standards (there are differing vendor implementations depending on platform which while annoying are largely well known how to navigate). Linux operating systems - the amount of incompatibility between linux distros is shockingly small all things considered.

I'm sure there are others I'm not able to think of as well, but this isn't special to the web by any means.