This has not been my experience. Part of it may be that I don't really do the whole "self-promotion" thing so well.
I'm pretty good at what I do. I have worked with many, many people that are much better than I am, so I don't let it get to my head.
But whenever I mention what I'm good at, it's met with snorts of disbelief. That's crazy. I am not claiming to be Superman.
I have a massive portfolio that proves what I claim. It has 30 or more (complete, documented, tested, and supported) repos, with over a decade of checkin history, and full source for a whole boatload of [mostly deprecated] shipping applications. Don't believe me? Clone the repo, and hit "Build." I have dozens of blog entries, articles, teaching series, etc.; all linked from my SO story. I even have the PDF manual for my very first engineering project, in 1987.
What I can (and can't) do is not a matter for debate. Like I said, I have worked with many folks that make me look like a piker.
Here's an example:
About a month and a half ago, I responded to an article, where the author claimed we "never finished" anything. This was what I posted:
>> I dare you to list three finished software projects.
> I can probably list 30, and point to the repos.
It's 100% true. You don't need to take my word for it. Simply look at my SO story. I link to it in my HN handle.
Someone that obviously did not bother to do exactly that, posted a challenge, basically calling me a liar. I responded by throwing the seed into the nest, and posting a link to my SO story[0]. They never responded, after that.
Like I said, I know that I'm pretty good at what I do, but I spent my entire career around folks that made me look like a beginner.
It's really, really sad that people seem to consider that kind of stuff to be a lie.
But I have been told "You know, because you're older, you'll need to ask for less" by recruiters (recruiters are the worst).
I've had testers (silly tests), be quite disrespectful, and use tone and engagement (or lack, thereof), to make it clear that this is an annoyance for them, and I should just "get it over with," so they can do something "more important," I guess.
I've had numerous recruiters suddenly develop "connection problems" on the phone, moments after I've made it clear that I'm older. They promise to get back to me, and I never hear from them again (I believe that kids, these days, call that "ghosting").
I've had initial screeners (I assume HR), do the same thing.
One pleasant experience was actually Facebook. They have been polite, respectful, and cheerful. I have not felt discriminated by them. I don't think that I want to work there, but I feel as if they would be approachable. I have had other FAANG companies that were shockingly rude, and that surprised and disappointed me.
Probably, the worst thing, for me, is the unwillingness to check my portfolio. It’s friggin huge. Many years in the making, with lots of shipping products.
I’ve actually been told that “I probably faked it,” and given a stupid binary tree test.