Because, in our society, rhetoric has become accepted as evidence. So, when Sally says "I used acupuncture and it helped me conceive", that counts as evidence.

Because, in our society, rhetoric has become accepted as evidence. So, when Sally says "I used acupuncture and it helped me conceive", that counts as evidence. When a creationist says "well, a banana fits nicely in my hand which shows an intelligent designer", that's evidence. This combined with the fact that the scientific community seems bent on publishing even when they have studies with no statistically significant result. I'm reading more studies of 50 people in two cohorts where one had 10 do something and the other had 11 do something touted as a breakthrough. In fact, it's evidence of nothing. So, the value of rhetoric has grown in people's minds and the value of evidence has diminished because people are publishing crap.