I feel like we got sidetracked into discussing exchanges. Although I admit trading bitcoin and making profit has become the only thing that newcomers care about but that is not what bitcoin is made for. Bitcoin was made to be a currency not an asset that you trade on some exchange whether centralized or otherwise. If you use it as a currency none of your arguments stand anymore.
Here is one challenge: try to deposit at least 0.005 Bitcoins coming directly from Coin Join outputs on three different centralized exchanges without getting your funds seized or questioned on any of the three exchanges. Anyone who is using Wasabi or Samourai knows this challenge can not be won.
I have mixed more than 0.005 and have paid lots of merchants both online and offline (face to face), even big regulated companies located in US and to this day I have never had any problems with fungibility.
I repeat my first post here; I'm not against more privacy in bitcoin but the problem is not with bitcoin protocol, the real problem is with centralization. Even if bitcoin were fully anonymous or if it were like this but 99% of bitcoin users were mixing their coins the centralized exchanges (and others) would still enforce anti-privacy rules. For example the exchange could force everyone to submit how they got their coins and provide a detailed transaction history to the exchange or their account would be shut down and their coins seized.