Yes, you can absolutely add a middle man to sort through the spam for you, and that "solves" the problem in the sense that you are trading money for time. It's no different than paying for a personal assistant to collect your mail for you and pass along the valuable stuff. That said, it's incredibly inefficient and most people, for most interactions, cannot hire a third party to handle those interactions for them.
So no, I don't think adding layers of middle men really solves the problem for most people.
The proposal was two middlemen. It's just an inefficient way to, as you (or somebody up the chain) said, charge for attention to reduce spam. Since the middlemen are being paid, most spammers won't hire them.
> incredibly inefficient
In practice, yes. In theory, it could be fantastic. Imagine, as a simple example, you have two early-career backend developers. They could each do the same search, or a middleman could do one search and share the highlights with each developer. The fact that you have overlapping demands and information opens up the potential for the work to be amortized, even if you're not adding any value as a middleman other than trading time for money.
I've heard that one of tricks recruiting agents use is to maximize mismatch without breaking the illusion of a perfect match, so that victim companies has to come back as often as possible, each time rewarding them with commissions. Value alignment is definitely going to be a problem.
So no, I don't think adding layers of middle men really solves the problem for most people.