Before HF19 minnows had 40 upvotes a day without "losing power" after the HF it's down to 10.
Various posts have suggested that minnows keep their voting power at 100% so instead of voting on everything that brings value to the community, each "curator" (read user) has started saving votes for the 10 "Best" posts they find in a day.
There is also the very common confusion from many minnows about where the money comes from. Many still think they are "paying" the author, which is simply not true, the pay comes out of the chain not from upvoters accounts.
I don't know why less "whales" and "dolphins" are spreading their votes around. One theory is that it's getting increasingly difficult to find quality in the continuous flood of copypasta and "help I didn't read the FAQ" that fills the "new" feed.
Just my two cents (which isn't even worth one cent)