This is about control. If you’re forced to upload ID, the government instantly has a watch list of people and associated sites. Then there’s the flexibility of the definition of porn. Once the legislation is in, anything regarding sex, sexuality, or gender education gets quietly reclassified. Because you know, to these people being anything but straight is inherently pornographic. Then you have a watch list of potential LGBT+ people and allies to harass.
Not only that but between the various web tracking technologies that advertisers use and people’s reuse of credentials for convenience you now have an easier way to associate a real identity with a specific person as they browse the internet. A boon to advertisers and other interested parties alike.