To clarify: for a large number of topic I find this completely fair and valuable to first have to build trust. But getting your research paper in front of other humans on a aggregation website seems like the one place where this for me falls apart.
Today any one from any corner of the world from any educational or non education place publish stuff, well moderation is tight and often it won't get through but I know a few friends who aren't in academia that have a paper up there who wouldn't have been as easily able to get a paper on anywhere else.
Maybe that's not a genuine concern but that often used to be the case and still is in a lot of invite first clubs/groups. I know credible people in the field who were and are working in relative isolation which leads to not being able to participate in sharing of ideas.