Two reasons:

• It is plastic. It will degrade into microplastics and will end up… in places where it shouldn’t. Water (from cleaning), inside of humans (and other animals) due to drinking water, breathing, etc.
• They are much harder to clean and keep hygienic. They get smelly much faster. They smell worse within a workout and they are hard to clean between workouts.

Buy cotton shirts/shorts. Avoid technical fabric.

The comments on this post are entirelly missing the point. Jesus christ lemmy. Yes, we know you like 3.5 mm jacks. That is not the point. The point is that FairPhone launched earphones with ANC with replaceable batteries. This is good!