he human brain isn’t capable of keeping track of enough entropy to create a secure password system.

What an idiotic argument, the level of entropy comes from the rules first and foremost, putting a 1 and an A together is the exact same entropy as using 2 and B. Randomizing it one way instead of another doesn't change entropy much.

More generally, it’s a big red flag when anybody thinks they can make a better system than publicly available and verified systems.

You completely fail to understand the argument. I'm not arguing my passwords are stronger, I'm arguing they are SAFER! because they are not stored on any system, much less 3 different systems, one of which could theoretically have a vulnerability.