Also, many people want to run Linux on their phone. About 7 in 10 smart phones run Linux, and smart phones are devices billions of humans use every day.
This is as far from the mainstream as you can possibly get.
Come September it will have been a decade since Apple dropped the headphone port - the world has moved on
Do an experiment. Jump in a pool with both your iPhone and your MacBook and see which one works when you get out.
Which you said aren't being made anymore. Which is factually untrue. The best bit is, they're still being made! And there's plenty of people who are still buying them!
Why? Because a $170 pair of closed-backs sounds infinitely better than the $550 Bose Quiet Comfort Ultra nonsense.
FiiO FT1 32Ω being a prime example, if you are looking for closed back suggestions :^)