I think you missed the point. Instead of posting a job to dozens of job boards, a company simply updates their HIRING.md file in a code repository somewhere. For technical positions, that would be easier to search.
That's much preferred than searching dozen of different job board aggregators and all the companies' websites that are not fed into such aggregators.
Plus hiring is typically done by non-technical people. They're not going to update a markdown file in a Git repository.