Yep.

Agencies funded by taxpayers provide grants to researchers.

Researchers produce results and write papers.

Researchers give the papers to editorial houses for free.

Editorial houses send the papers to peer reviewers.

Peer reviewers review the papers for free.

Original authors make required changes for free.

Editorial house send proofs to authors, who check and fix them for free.

Editorial house charges absurd amounts of money for people to read the papers.

TL;DR Editorial houses suck money from everyone while creating near zero value.

So go ahead and create a free editorial house, what is stopping you? They are not government agencies, you don't need special permission to create one, so just go ahead and create "Nature" competitor.

Haven't you thought that if everything is so simple, then why why isn't anyone doing this for free? Why all those scientists keep sending their papers to those publishers that end up hiding them behind paywall?

Have you thought for a second about that? That there is some incentive that is more than just silly scientists sending their hard worked papers to greedy publishers because of ... what?

And did you know that you only need to pay for access if you want to read it from publisher? Did you know you could just contact author and ask him to share the research with you and author can send it to you that without publisher's permission and for free (provided he wants to give his research to you for free of course)?

The problem is the same as internet newspaper. You don't need to pay to know the news, but if you want to read certain newspaper it will bill you money. News itself is free. The work newspaper does is not. If you are not happy with some newspaper, maybe just don't buy it?