This is true (iPhones, iPads, and plenty of Android phones these days), but can be mitigated by carrying a USB-C to 3.5 mm audio adapter in the pouch that contains the IEMs. I wish people didn't have to, but it's a straightforward solution that widely improves wired compatibility.
Adding a small adapter to where you carry your wired headphones fixes the problem of the current reality where many devices do not have audio jacks. My assertion is to provide a practical solution to the current state of affairs, instead of claiming that the present is better than the past state of affairs (where there were ubiquitous audio jacks) due to audio adapters.
Due to forces beyond the individual's control, it's highly unlikely that audio jacks will once more become ubiquitous, so the second-best outcome is for wired headphone users to start carrying an adapter.
