You can get a phone number without registering it to your name, but otherwise yes. Most people's phone numbers can be found online, as well as reverse (find someone's name by phone number) .

Requiring strong ID verification (from government ID or the digital ID we're discussing) helps protect against identity theft. Other countries I've lived in that use very weak forms of ID ("a utility bill in your name") seem like much bigger paradises for identity theft.

Practically identity theft the way you think about are very rare in Sweden, more common are social engineering attempts like calling people and asking them to use their MobilBank ID while the caller logs in in their name.

Remember that personal ID numbers are not a big secret in Sweden as well, and still we don't see any big problem with that.