[isametry]

If data plans weren't tied to them, Gen Z probably wouldn't have phone numbers at all anymore. (Well, at least in those parts of the world where a data reception no slower than 3G is ubiquitous.)

If you think about it, the whole concept really does stick out nowadays. The idea of this unique, static (or at least not easily changeable), non-descript identifier tied only to you and your physical device is very much a product of its time.

Phone numbers only continue to exist by momentum – if a similar thing were to be implemented today, it would never catch on so universally.