Some of it is probably an artifact of mobile plan pricing being quite dependent on who you were calling when cell phones became widely available. I (still) have an area code that's the result of who I tended to be calling on my cell at the time. Hasn't been my "home" area code for many decades. (Not that I actually have a landline any longer.)

I think it's the other way around: Since calls were routed geographically, and it's not apparent to the caller whether they're calling a landline or mobile phone, it also made sense to price them geographically (at least before the marginal cost of the incremental call-mile went to zero).

I didn't actually even live in the area code at the time but had outdoor activities with people who did live in that area code who I might call from my cell. So that's what I chose. And, by the time I switched carriers, phone number portability was a thing.

Funnily enough, that area code became something of a status thing in an era when near-in suburbs got "kicked out" to a suburban area code when a lot of people were getting second phone lines for modems. There's a Seinfeld episode related from a different city.