>You don't change your number if your phone gets hacked.

This

You don't change your ISP if your pc gets hacked.

If your phone gets "hacked" (IE a virus etc) the phone gets wiped.

It's an important distinction because one is not clicking dodgy links and cyber health, the other is making sure you think before you hand over bank details. Being scammed isn't "shes stupid" it's "she was caught off guard, or without knowledge to defend against the scam"

The change of number is usually because when one person falls victim to a scam the number is passed around because they're more likely to get scammed again without the extra knowledge.