So, this other person ... what motivates them to do it? They don't get paid, and they don't really care about the journals (per say). Presumably, they do it for the good of their profession, or for fame, or because having a lot of influence in the field makes it easier for them to secure tenure / promotions / grant money.
We do it for the good of our profession. All I'm asserting is that the difference between the current system and a self-publishing free-for-all is that under the current system peer review for any single publication is performed by a small (3-5) number of people. I might review one or two publications per year (for no financial compensation, as you say) -- but in exchange for this effort I get to read dozens of papers which have been peer reviewed to a similar standard. In a free-for-all I'd have to put in the effort of peer reviewing every paper I read. That's a huge amount of work.
> In a free-for-all I'd have to put in the effort of peer reviewing every paper I read.
You seem to be criticizing a straw man. Nobody is suggesting that peer review should stop. We're suggesting that there's no longer any reason to link peer review with publication and access.
The real value is added by the reviewers and the authors, and they can keep on providing that value the same as always. It's the publisher who has become nearly superfluous, yet it's the publisher who charges boatloads of money for access.