I've had so many conversations that go this way.
And I've also been pretty surprised over the years at the number of people that I'd expect to be financially literate b/c of their jobs, education, whatnot that are not.
Underlying the strategy you're using for the HSA (and which I am too) is the fact that we have the excess cash and savings rate to do so. Very few people I know can get to the point of maxing out a 401k. Heck, my company has an average employee age of ~50 and avg salary that's a bit shy of twice the national household median income. Only between 10 and 20% of our staff contributes at the level of our SIMPLE-IRA limit (which is just $12,500/year, $13,500 with catch-up). And most have working spouses doing well. I don't get it.
But anyway, if they aren't even doing the basics, more advanced stuff like backdoor roths, hsa hacks, DAF strategies, tax loss harvesting, ACA hacks, etc aren't going anywhere since execution is also predicated on some combination of not having healthcare expenses or having enough excess cash that you can defer withdrawals.
If you spend nearly all your earnings, this stuff is really easy to ignore because it's so irrelevant.
I've always been a saver and paid attention to this. I was doing some documentation clean up and was reminded that I did a tIRA to Roth conversion in 1998 (the first year or two of the roth) in my very early 20's. 20 years of thinking about this kind of stuff made reading the Mad Fientist post relatively easy. Without a lot of context, it's not easy to grasp!