Most of time it's billed as law enforcement fighting tool. If people can't have anonymous cell phones, once you capture one criminal phone number, you can quickly look at who they call and since they can't be burners, you figure out the criminal network.
Also, if you have restrictions of speech in the country, it's great way to de anonymize any speech government says is illegal.
There a significant difference between "the user can be identified fairly well if you can get access to sensitive stuff" and "the owner is always explicitly recorded in a searchable database".
The free anonymous internet was only ever a ruse to get people to use it so the CIA could spy on them. DARPA, folks, created a “free as in beer” global surveillance network and we all bought it.
Not that we didn’t get anything in return but the idea that the worlds foremost military industrial complex just gave this to the world because they loved us is laughable.
Also, if you have restrictions of speech in the country, it's great way to de anonymize any speech government says is illegal.