Boy, it's a different company doing this now, but this is definitely still something that is happening, especially in mobile.
Apple is still actively developing Safari and JSC and implementing standards, Microsoft basically COMPLETELY FROZE browser improvements for 10+ years. Worse even, they pushed proprietary Microsoft-only solutions to try to lock-in people.
However, when Netscape died, Microsoft did a 180 and went from the leader in promoting the web to the absolute worst obstruction. It seemed like they completely de-funded their IE development team.
[1] https://en.wikipedia.org/wiki/HTML_Application
[2] https://en.wikipedia.org/wiki/HTML_Components
[3] https://learn.microsoft.com/en-us/previous-versions/ms530752... (previously was just filter:)
During that era was a peak of browser innovation. IE5 and IE6 contributed a lot of things to web standards. They contributed a bunch of things that web standards eventually rejected too, but that was the risk of innovation at the time.
It was the period between IE6's last feature update and IE7's first release where Microsoft declared the browser wars "finished" and disbanded the IE team entirely that was the Darkest Age. So about 2001-2006 were the darkest few years.
It certainly had repercussions until around 2010, but the worst "sabotages" were done and gone by then. "Legacy" problems.
You could see all the new features, you could use them, you could design your site around them. But so many people refused to upgrade, so as a web developer you were forced to do stupid things to make IE6 work.
And it's not like IE7 was that much better. You needed to put effort into making that work too. At least Chrome and Firefox would usually both do the same thing.
From 2010 until about 2020 I would say the standard committee took hold and they have been quite busy with other things. Since JS is a language defined by committee it can take quite some time for people to agree on APIs which is a subjective topic. The last thing the standards body want is to introduce an API and then deprecate it in favor of another API slightly later.