For the record I'm not saying you're lying (and I don't think you are). It's kind of analogous to what I said about self-reported past experience in the sense that I would expect (maybe expectation misplaced?) that somebody who has plenty of experience on the hiring side would better understand what happens on that side of the process.
I think your claim that employers are "not desperate" is probably true to some extent, but if you're screening for say 30 candidates, the cost-benefit analysis of spending an hour each looking at their github profiles might not work out unless in the "most desperate" of cases (and if they're desperate to the point where if they can't hire a superstar they'd go out of business, then you wouldn't want to work there anyway).
TBH my belief is that some FAANG or famous school is a better signal than self-reported experience on a CV. You might disagree (and there are reasonable arguments on that side), but at least whether one worked at a particular company or went to a particular school is an objective fact, while things like "built a well-received service with millions of users" can mean very different things. The supposedly rigorous hiring/admission process of FAANG and famous schools can be a useful thing to know because the hiring process could be quite similar, and thus a useful predictor whether a candidate is likely to do well on the hiring game at hand (not necessarily a good employee, that's another question).
I don't think work quality is obvious for those halo effects you mentioned. There's just some fuzzy correlation (about being in FAANG and interviewing performance) that lazy interviewers/managers tend to mistakenly conflate with employment suitability. There are many reasons why hiring tends to be broken, which I'm not going into because it would be a book length thesis in itself, I'm just saying there's no way code quality of your past work would be "obvious" unless somebody actually spent a couple hours reviewing your code. Nobody would do that unless there's some other signal indicating that that might be the case (and in 99% of the cases they wouldn't do it even if the signals are there).
So my point is that if you proceeded with the assumption that it should be obvious to employers that you're employable... maybe that's not a great assumption. I definitely agree that most of the time companies aren't "desperate" to hire -- and TBH you don't want your future employers to be so desperate. If you're not getting offers (and you want to), maybe you'd have to spend a bit more effort advertising yourself instead of relying on potential employers' desperation.