They were folding, too.
"Firefox downloads and enables the Google Widevine CDM on demand, with user permission, to give users a smooth experience on sites that require DRM. The CDM runs in a separate container called a sandbox and you will be notified when a CDM is in use. You can also disable a CDM and opt out of future updates by following the steps below. Once you disable a CDM, however, sites using this type of DRM may not operate properly."
They rather lost a unique selling point. Not implementing EME/DRM is a form of protection of the user against malware.
A well-hidden build of Firefox to silence the people who accuse the Mozilla Foundation of betraying their principles...
This really matters because so many of those exploits relied on other features to actually run the payload. Not having any of those in the first place is a big attack surface reduction, even if the politics are legitimately debatable.
But they ended up including DRM in their browser. So they're traitors and hypocrites, right?
This was absolutely NOT wanted by Firefox.
They were the only browser to represent the users in this fight.
Don't put Mozilla in the same group as those other traitors.