Monero amounts and addresses aren't even visible on it's blockchain thanks to Confidential Transactions and Stealth Addresses. Completely hidden. Less than a cent to transact too.

So yes, it is true, Monero is a great tool for privacy.

Coinjoins don't offer privacy, merely ownership obfuscation, a weaker form of anonymity. Nothing is hidden. Also it's slower, expensive, and tedious vs Monero.

Lightning isn't more private either. Lightning wasn't optimized for privacy. It was designed around cheap and fast payments. Receiver privacy in particular is terrible and there are many ways to probe the network. Incentives also naturally lead to less privacy (cheaper and more succesful routing require shorter routes thru massive hubs)

Here are literal LN devs telling us lightning isn't private:
bitcoinmagazine.com/technical/state-of-bitcoin-lightning-network-privacy

Also, another of many things to consider is that absolutely no one uses lightning on Darknet Markets. A place where privacy is paramount, with ultimate skin in the game, Monero has massive disproportionate adoption.