Yeah, it's a ridiculous take because the specialized things you have in a nice onebag setup are not going to be easy to find in a random store. Just replacing the backpack itself is going to be a major issue if you are outside of the United States.
The only reason my setup is worth more than $200 (maybe $300) total is because of my glasses and contact lenses.
Mostly though i think it comes down to the old joke “everyone who spends more than me is wasting their money on exorbitant whatever and everyone who spends less than me is a cheapskate.”
https://jeremymaluf.com/onebag/
The list looks like the very definition of brittle to me. Every single item is from a different manufacturer, possibly rare, bespoke, or hard to find (a Japanese version of a highly technical jacket, underwear that even says it’s hard to buy in the description). We’re way beyond preferring wool socks here.