As someone who got through audiophilia stage and back, most people do not expect phone DAC to output high-res audio. They just want to plug their wired headphones on the go, without extra clutter.

You’re very unlikely to hear the difference in a hustle and bustle of the city, and if you want to settle in a quiet place to enjoy your collection in all its glory, you have plenty of better options available.

Headphone jacks are still absolutely valid for many.