I don't believe you've understood the initial suggestion, so let's go back. Many people would prefer to make their contently freely available to as many people as possible. In practice this is a copyleft license. Such licenses are of the form that the licensee, such as YouTube, is granted a license allowing them to use and do anything with this content - so long as the same rights are extended to any others who are provided access to this content.
Unfortunately most sites, including e.g. YouTube, do not allow this. They require uses to agree to non-free licenses. One of the primary reasons they do this is to help prevent and obstruct competition. YouTube goes a step further by making it against their terms to contact users for licensing inquiries. This is all extremely anti-competitive.
So what can be done?
Well that's pretty easy. Free licensing would in no way meaningfully burden or, in itself, harm YouTube or other such publishers. If a site primarily generates revenue by providing free access to user generated material, then require that the users be allowed to enter into free licensing agreements with that site, if they so wish. While creators could be incentivized to agree to non-free licenses, such as by payment, the content itself would be treated identical whether a user chose to enter into a free licensing agreement, or a non-free licensing agreement.
The goal is to turn "free" into free. And in the process help spur more competition and a wider spread of information and knowledge.
Here's the point of disagreement, then: I don't think YouTube prohibits "non-free" licenses, and I don't see how their terms of service can be construed as such. I also don't see anything that would prevents users from contacting content creators for licensing inquiries. Could you point out where in the terms these exist?
YouTube itself refuses to agree to free licensing agreements with content creators. It forces them into a non-free agreement, or nothing. This is done, in no small part, to deter competition.
The term is 4H, "You agree not to solicit, for commercial purposes, any users of the Service with respect to their Content.".
That would include licensing requests. Commercial purpose does not mean e.g. only for pay. It has a broad definition that would almost certainly include a peer to peer company reaching out to content creators to try to host their content, even for free. Once again, that is their exclusively for anti-competitive purposes as I doubt even users that just want to share their content with no expectation over remuneration would opt in to having any and all proposals preemptively killed off.
Unfortunately most sites, including e.g. YouTube, do not allow this. They require uses to agree to non-free licenses. One of the primary reasons they do this is to help prevent and obstruct competition. YouTube goes a step further by making it against their terms to contact users for licensing inquiries. This is all extremely anti-competitive.
So what can be done?
Well that's pretty easy. Free licensing would in no way meaningfully burden or, in itself, harm YouTube or other such publishers. If a site primarily generates revenue by providing free access to user generated material, then require that the users be allowed to enter into free licensing agreements with that site, if they so wish. While creators could be incentivized to agree to non-free licenses, such as by payment, the content itself would be treated identical whether a user chose to enter into a free licensing agreement, or a non-free licensing agreement.
The goal is to turn "free" into free. And in the process help spur more competition and a wider spread of information and knowledge.