Not everyone.
Do you know that you can get rejected by arXiv if they think your publication is not worthy of their publication.
It's an open access journal masquerading as pre-print server. There are other much more open pre-print server.
On top of that the chance of finding something as you suggest becomes that much more difficult. Smaller findings get published now in a more controlled scenario and get lost in the stream.
Major journals are a net positive for surfacing important science.
Discovery is a search problem and its pretty clear that we have the technical capacity to solve that problem if there is enough of a signal from wide-spread peer review.
Major journals become those that re-publish and report on the big debates and discoveries of the actually peer-reviewed journals and this would be the work of "journalists".
Non-experts sometimes bring perspectives that gatekeepers are blind to.
For discoverability. Someone's trivial finding may be someone else's key to a major breakthrough, but little good it does if it can't be easily found