Thanks for the detailed explanation. I'm still not sure this overcomes the marketing budged differences between entities like "AI Slop Co" vs. "Independent Artist" or "Ford" vs. "Independent Mechanic". There's also the fact that the heaviest advertisers are often the brands I'm going to be least interested in regardless of any other factors[1]. Yes, you can get ad relevance to some local maximum where I do see some stuff I'd actually buy, but optimality is forever out of reach because the products I really want to know about probably spend almost nothing on advertising or have direct competition from an entity like Microsoft that will pour $millions into their ad spend.

[1] VPNs are a perfect example here. I would never use NordVPN because they advertise on every square inch of YouTube. This suggests to me that they're either charging too much for what they offer or they're getting money from their actual customers and the users are simply the inventory they sell to those customers.