> Linus doesn't release a linked version of the kernel
Linked to what? Any new change in it must become open, which is the whole point of "viral", copyleft GPL license, in contrast to permissive ones.
> They work more for users than other organizations that you would try and replace them with.
They put their users in dangerous dependence on Google. This is not what I would consider more useful than alternatives. It may be more useful in the short term, since it still works, but in the long term it's dangerous. In this sense it's not much different from good proprietary software like MacOS.
> I don't know what you are referring to.
GrapheneOS didn't completely fork Android. They still follow Google's development strategy, which only benefits Google and not users.
This is false, https://www.gnu.org/licenses/gpl-faq.html#LinkingWithGPL
> Having a working system providing competitive value to others is much more important.
I don't consider dependence on Google as "working for the users".
> The good reason is that those devices can't provide industry standard security.
Obeying Google is not "security", even if it's the industry standard.