Also in some countries keeping your number isn't cheap. And even when it's technically easy, your phone plan might be provided by your employer, in this case it might be very tricky to get your number migrated when you change jobs.
And yes keeping my phone number as it was would cost me $80/month. With a provider i hated like the pest.
At least 2 of them are now reused and given to other people.
I rant about this for a while now, and many people say stuff like "you can just take your phone number with you". Its on par for me with "I have nothing to hide, why would i worry". Its just short sight and projecting personal use on the world.
Postal addresses are Name + Address so get invalidated automatically when i move. Therefore i would argue are also better.