My thoughts about putting manuscripts on web sites has evolved over time.
Early in my career, it seemed like putting stuff out early was best; it gave some property rights. But I am inefficient, and reviewing/presenting changes your paper. The latest version is not like the early version, at least for my ambitious work. Sometimes the titles even change. You lose control of the manuscript and where it is circulated.
If the paper evolves, you can be screwed on the cite count—I have one paper with lots of cites, in total, even though the paper is cited in lots of different ways, and under different titles. Or even for incorrect points, since things were changed significantly over time.
And of course, referees routinely google a paper they are reviewing. There goes the blind review process. That problem is not large anyway—I would never submit a paper until it has been presented someplace first. Meaning that the reviewer likely knows who wrote the paper even if I did not put it out on the web first.
My current decision is not to put manuscripts on web sites until it has ‘settled down’ for a while. But that raises the possibility of losing the property rights to the idea.