If employers and funding agencies would stop using publications in private, for-profit journals to evaluate whether researchers should get to keep their job or have their grants renewed, then this wouldn't be an issue.
This is a good point, but it actually goes further up the chain. The universities in UK, a lot of their funding is driven from publication record of their staff. So they too are just responding to incentives - https://en.wikipedia.org/wiki/Research_Excellence_Framework
Or even just weight any open access journal more than any closed journal.
That way you can still use historical publications to evaluate researchers on day one, and the evaluations will be accurate assuming most researchers historically each published the same percentage of articles in open access journals, but nobody will want to publish in anything but an open access journal going forward.
