It is much stronger that that. The built in "coinjoin-like-function" of Ring Signatures (15 decoys) are only 1 of 4 layers of Monero privacy tech. It is one of the weakest parts and only for senders. Dandelion++ also obfuscates IP origination.

The parts that make Monero really shine are:

Confidential Transactions completely hides amount

Stealth Addresses completely hides reciever

Simple example of a Monero transaction:

~6% chance Alice sent $[?] to [?]

Unlike simple coinjoins, the transaction graph connecting senders to recievers doesn't exist. Amounts are not available to analyze either. All you could know from just looking at a blockchain transaction is a 64-character string maybe signed a Monero transaction.

How much? To who? That is unknown.