It's very simple: The fandom is growing more and more "leftist" (I am using this term the way the puppies are, referring to anyone who isn't part of the alt-right group that makes up the puppies. You know, "leftists" the kinds of people who don't hate feminism, who like to see inclusive fiction that isn't just MANLY WHITE MEN SAVING THE DAY WHILE WOMEN ARE THERE ONLY AS SEX SYMBOLS! ...Minorities need not apply.) and rather than an organized assault on the core values the puppies love it's just quite natural that the people used to vote for things they liked.
Sure, there may be an backlash against a writer who is racist, homophobic or otherwise against what the majority of the fans like but I would like to point out that if a writer would officially come out to support things that the alt-right hates then there would be a similar backlash, with the difference that as the non-"leftists" are reducing in numbers the backlash wouldn't be quite as big. ...And why am I speaking hypothetically since this is exactly what the puppies are.
Another problem is that everyone likes to think that they make up the silent majority so the Puppies are a reaction to seeing that the world does not work the way these people assumed and instead of admitting that they and their beliefs are less popular they conjured up some conspiracy theory that they could blame instead.