some cases 100% is sold and nothing is left in stake.
This is highly unlikely. If it was the case then even with a 50/50 model the price will tank (given your scenario where most people are selling all their token). A 25% increase would only translate to a deeper dip, but the impact of a mass sell action would still be obvious even with the 50/50 ratio
I don't there is no directly correlation between increase in author reward and selling pressure.
It is case between price stability and better distribution.
you are within your rights to think that way, but the math points the other way, and I am not at all right, but you don't have to be that smart to figure it out, you just have to see how the market has behaved and draw your conclusions based on what you see!
It's simple just follow the money trail and do a couple of sums!