In the first place? We kinda did to begin with, you would phone the operator and say the name of who you wanted to phone.

Introducing phone numbers simplified this, given the operator would have to know or lookup their name, and allowed for the future introduction of automated systems. Such systems were analogue and DNS was far more advanced than them. I guess the telephone becomes so widely used and integrated under that system that it still uses a similar interface today, albeit with a cluster of different modernised interconnected backends