Monero's technology enables private and untraceable transactions. It's amazing and I own some just because of that property. Seems to be the only cryptocurrency that still aims to be an actual currency.
You're right about the altcoins though.
Not exactly. The decoy inputs/outputs provide some plausible deniability when you look at a transaction in isolation, but over repeated transactions it gets gradually lost. It's not enough to pin you as a criminal with 100% certainty, but it's enough for the police to keep an eye on you and wait for you to slip up.
Doesn't this require an exchange to provide external information? It is my understanding that it's impossible to correlate transactions using blockchain analysis alone.
or a donation address, or a cooperative counterparty when you buy/sell something (think darknet market that got radided, or a payment processor that sells its transaction information).
That, combined with the privacy makes it seem really usable. I’d love a way to make cheap, private, digital payments