Sorry to say this, but this is natural. Writing patches is easy. Reviewing them is hard. Writing patches (and getting them accepted, merged) is rewarding and demonstrable (as a form of achievement). Reviewing patches, educating new contributors is sometimes rewarding, sometimes not (it's an investment into humans that sometimes pays off, sometimes doesn't), but mostly not a demonstrable achievement in either case. Therefore there is incentive to contribute, and hardly any incentive to review. This is why reviewers are extremely scarce in all open source projects, and why all sustainable projects optimize for reviewer/maintainer satisfaction, not for contributor satisfaction. As an external contributor, you just don't get to allocate scarce resources financed by some commercial entity with no relation to you.
If you want to become a maintainer, or at least want others to review your stuff, don't start by writing code. Start by reading code, and make attempts at reviewing code for others. Assuming you get good at it, established project members should start appreciating it, and might ask you to implement some stuff, which they could be willing to review for you. You first need to give the real kind of effort before you can take it.
And this is why "open development" is a total myth today. Resource allocation and work (chore) distribution are aspects of reality that completely break the wide-eyed, bushy-tailed "new contributors welcome" PR message. Opening up the source code (under whatever license) is one thing, collaborating with randos is an entirely different thing. Can you plan with them in advance? Do they adhere to your deadlines? Can you rely on them when things break? When there are regressions?
> you get ghosted if you don’t have a @google or @redhat email address and really the only way to become a contributor is to be buddies with someone who works on the project already
Yes, and the way to become buddies is to help them out where they are hurting: in their infinite patch review backlogs. Of course, that means you have to invest a whole lot of seemingly thankless learning, for the long run's sake. You have to become an expert with effectively nothing to show for it in the git history. It's totally fair not wanting to do that. Just understand that a ticket that remains open indefinitely, or an uncalled-for contribution that never gets reviewed and merged, may genuinely be better for the maintainers than taking on yet more responsibility for your one-off code contribution.
> I have considered going to one of the CNCF committee meetings and being like, hey you guys are not accepting new contributions which goes against your mandate
According to the above, I bet that "mandate" is a total fake; a PR move only. It does not reflect the actual interests of the organizations with the $$$, which is why it doesn't get followed.
You are right that those orgs should at least be honest and own up to NOT welcoming newcomers or external contributors.