No it is not, this is a myth. As you also can use free software on closed OS, which happens to be the standard

Why does it "happen to be the standard"?

Because people use it. At the end of the day, usage is what determines what's standard.

Whether a particular person can opt to go for something non-standard (eg. Linux) doesn't make what I said any less true.

And the problem is that the non-standard person can't expect the same level of support (eg. Linux drivers for obscure hardware).. because devs and companies won't care so much for any deviations from what's standard.

The point is that user generated or govt establish frameworks can b used as basis

That would be useless if people (both end users and web developers) don't use it.

The Mozilla Foundation created their own browser. Yet they are dying since they are getting abandoned by both web devs and end users. Creating your own does not solve the problem.

If web devs design for Chrome and Chrome adds Chrome-specific deviations from the standard, it's gonna be extremelly hard to keep up, which is what is happening with Firefox.. they can't keep up, they keep receiving reports of problems because websites are developed for Chrome.

This is already the case, you can choose not to use FLoC. Nothing changes here.

Yes, In there I was just describing how things work. As I see it.

Please learn the difference between Browser engine and web standards, nonsense you talk here

Web standards are just a set of rules that hipothetically Browser engines follow.

In practice, however, no browser engine actually follows the standard 100%, since they all have their very own extensions or try different optimizations that result in differences of implementation.. Google keeps adding their own spin on things at a pace that is hard to keep up for any other browser.

If it were possible for web standards to be really, truly, and fully respected, then indeed it wouldn't matter what browser you use. But that's not what the reality is. There are websites that work and look different in Chrome than in Firefox.