I don't think its surprising that people aren't deciding what turns them on based on population statistics. I'm no expert, but the consensus of what I've read and heard is that by and large people aren't deciding what turns them on, period. They may choose to constrain their behavior or not act on certain desires based on what society finds acceptable, but that does not really change their sexuality.
However, if you feel alone, ashamed, afraid to reach out to others, etc, having a sense for how common certain kinks are can be extremely useful information. The objective of these statistics isn't to tell you what sexual behaviors are good or bad based on popularity... the very definition of a kink is that it is uncommon.
Separate from this topic, I find that understanding of what's "mainstream" is completely irrelevant to informing my own decision making.
It is mainstream to have a gambling addiction, be overweight, be heavily in debt, etc. The fact that something is "normal" doesn't tell you it's good.