This is the nomad dream. Have a single phone service and wander anywhere on the planet with it. No more having to swap SIMs out on every border, being unable to use text-based 2FA, forcing friends to contact only via messaging apps, system messages in a foreign language, etc. It's not the coverage; that's mostly good. It's not the price; mostly SIM cards and plans are cheaper when travelling than they are at home. It…
Personally, I still buy SIM cards (or, more recently, eSIM plans). Not so hard, but way cheaper, and you can get a local number and use with local services that require one.