“This is the story of the revelation in late 2013 that Bitcoin was, in fact, the opposite of untraceable—that its blockchain would actually allow researchers, tech companies, and law enforcement to trace and identify users with even more transparency than the existing financial system.”
Monero comes the closest, but there is a possibility that ring signatures could be broken in the future for sure.
Ethereum supports anonymized tokens and rollups too, if you choose to use them.
That’s the difference though. On Ethereum you have to choose to use them. On Monero it’s private by default. And that’s the way it ought to be.
If you’re using the anonymized tokens then your transactions are private by default.
Anonymization requires a bunch of computational overhead which means that anonymized transactions cost more to execute, all else being equal. So a blockchain where you can choose whether you’re using anonymization or not depending on your particular needs is better than one where it’s forced on every transaction.
Bear in mind, Ethereum is a platform. It has many different tokens with different properties running on that platform, some of which are as anonymous as Monero. Use the ones with the properties you need.
Oh, I see what you mean now. I have heard of privacy projects that are anonymous sometimes and not anonymous at other times like Zcash and was under the impression that is kind of what you meant.
Those sorts of things exist on Ethereum too. There are also “mixers”, like Tornado Cash, that can anonymize a particular transaction using a normally non-anonymized token. The Ethereum philosophy is to provide a broad range of tools that can interoperate with each other, allowing people to use whichever ones suit their specific need.