I didn't see any sarcasm tags on your comment, so I'll take it at face value and disagree. Two quick examples:
Google Chrome went from proposing a new WebAudio method called "start" to deprecating and removing the "noteGrainOn" method it renamed in the span of 12 months. Any sites using the original spec stopped working, some within a year of being released with the latest and greatest spec, one of which was Google's "WebAudio Playground" demonstration site. (There's a fun bug on file where that team had the browser team push back the method deprecation by a release so that they could fix that one website).
Google released Polymer in 2015 or so. Apps written using the latest version of that in late 2015 stopped working at some point in 2017 on Google Chrome.
Web browsers stopped being even a little bit backwards compatible around 10 years ago.
You are right, of course: if you use new proposals that have not yet been standardised, you are at risk of them breaking in the future. (I've been bitten by this at a previous employer that insisted on using Polymer as well. Don't get me started on that.)
When you stick to standardised features with multiple implementations, though, I think in the vast majority of cases you would've been fine. (This is also one reason why I was against using Polymer.)
(Obviously this does not cover all Electron features, which is why I don't consider browsers to be a replacement for Electron, at this point. I'm merely stating that it's very much possible to target browsers without having to concern yourself much with their rapid pace of development.)
Gah, Polymer. Glad to hear I'm not the only one bitten by that...
(Did a single site with it, worked for a year and then for 6 months only in Safari/Firefox, and then we ported it to sit atop another Google project... ¯\_(ツ)_/¯ )
Google Chrome went from proposing a new WebAudio method called "start" to deprecating and removing the "noteGrainOn" method it renamed in the span of 12 months. Any sites using the original spec stopped working, some within a year of being released with the latest and greatest spec, one of which was Google's "WebAudio Playground" demonstration site. (There's a fun bug on file where that team had the browser team push back the method deprecation by a release so that they could fix that one website).
Google released Polymer in 2015 or so. Apps written using the latest version of that in late 2015 stopped working at some point in 2017 on Google Chrome.
Web browsers stopped being even a little bit backwards compatible around 10 years ago.