In China the digital boarding pass QR code changes every 30 seconds preventing screenshots or photos of it from being used. But as they're currently implemented in the US it's no different than paper.
The bigger issue is how bad airline apps handle anything even slightly out of the ordinary like itineraries including codeshare segments or just randomly have server problems. I fly 50+ times a year and am able to actually use the digital boarding pass only ~95% of the time.
Exactly this, they're best used as a tax free investment account rather than anything health related. If you're on a plan with high enough a deductable to be eligible for an HSA and can afford it you should max out your HSA contributions before even a penny of unmatched 401k contributions. Personally I'd argue that you're better off maxing out the HSA and using post-tax money to pay medical expenses unless close to the end of your career. It's one of it not the single most easily taken advantage of ways to not pay tax at all on a long term investment.
The system is indeed stupid but the least you can do is take advantage of it where possible and for the middle class the HSA is one of the best ways.