Forcing researchers to do anything is a bad starting point in an academic system that individualises institutional problems. The average researcher didn't create the mess of academic publishing. The pre-prints should then 'count' as a 'real' publication as a peer-reviewed journal article would.

If the academic system still runs on valourising academic publications in 'top-tier' journals, most of which are published via commercial publishers, then it is actually the responsibility of the funding councils to provide funding to researchers so they can publish in them.