That's already happening in Australia - it's being sold as anti-trolling laws.

Aus Gpovt website: The Bill is also an important part of the government's commitment to protecting Australians from online harms. It will empower Australians to 'unmask' the originators of anonymous defamatory posts made on social media, where the material is posted in Australia. In doing so, the Bill will seek to centre defamation disputes on the relationship between the victim and the author of the defamatory post.

I haven't read the whole page yet, or whatever representation of this bill this is, but this jumped out at me:

If the poster cannot be identified, the Bill will enable victims to treat the provider of the social media service as a publisher for the purpose of potential defamation proceedings.

This enforces what is known as KYC, Know Your Customer. It's the end of anonymity. It says to hosts, like Reddit, for example, and Twitter, that they have to verify identity or they are liable for any defamation if the poster's identity cannot be verified.

This is an absolute nightmare bill. It ends the ability to anonymously post anything on the Internet. Bad news.