If authors would simply ONLY submit their works to open access journals and publications, the parasites would disappear.
The problem here is that someone needs to organize these things. Someone has to pay for the bandwidth, buy and run the servers, spend effort soliciting reviewers, run the reviewing software, respond to questions, request ISBNs, submit the work to indexing sites, etc etc etc..
Open access journals address this by having a publication fee, or by advertising, or by seeking volunteers and asking for charity. Paying for publication gets blurry with vanity press, and advertising ends up sucking up to the advertisers. Volunteering and charity seem wonderful, but have to compete with lots of other worthy causes.
In CS, most of the major publishers allow you to post a copy of your paper on your personal website (as long as you also link to the official version). Finding papers outside of the paywalls is only difficult when the authors are in industry (but those aren't the publicly funded papers you're talking about anyway).