s/some/most/, especially if you're counting by market cap or number of users.

Monero has public transactions but the recipients and senders' addresses are encrypted so you can't really trace it to wallets

Every UTXO is also randomized as far as input selection and distribution and also the way they're labeled as they travel through the system. For the simplest example, reference early monero code (at the time BMR, and MRO) where Borromean Ring Signatures were used, where the same operation is performed multiple times per-input effectively mixing inputs at the atomic level, rather than in later iterations (RingCT, Arcturus, etc) that extended this further to obscure also the amounts of these inputs and to trim some of the inefficiencies of Borosigs.

I think I got the below right, correct me if wrong:

What's stored in the blockchain that makes it work are public keys, and how you can talk to nodes who can append to the blockchain have to work over a network. You can always walk the whole chain at any time and account for all the activity of all public keys, and that is actually required because it's the primary way that the network knows "who" has what.

So what connects the public key to a person?

If:

- private keys are never in the hands of a third party (public keys don't matter), and

- transaction processors/miners are only available over secure channels that somehow dissociate the involved keys from loggable networky things like IP address, and

- information like IP address is not stored in the blockchain,

then a blockchain would be untraceable to anyone who does not have a complete view of all Internet activity between all the participants.

Anyone with your private keys (which you can make more up any time you want) could transact under those keys as long as they can talk to enough processors/miners through any transport method, and alter "your" stuff, that's why you guard those with your life.

Private blockchains. Imagine a crime cartel with a private blockchain. Obviously they are not KYC. You can withdraw funds from the cartel, or pay for cartel services with the coin.

Ironically, a version of this was in private fiat currency - the coins in the John Wick movies were used this way.

That's still a traceable blockchain though, just privately kept. As soon as you start keeping a ledger, you make transactions traceable. With a single or low number of ledgers, network analysis becomes easier the more heavily each actor uses the currency as well, compromising anonymity.

Private blockchain is a term that refers to blockchain tech that does not divulge balances and transaction history without being a signing party to that transaction or without a delegated 'view' key created by the keyholder for the purposes of the audit. It's a confusing term which should have a better name, I agree.

For an example, most cryptonote networks function this way unless they have explicitly damaged or disabled the functions responsible, like in the case of Electroneum.