How do Crowdtap surveys disappear?

Do they get taken by other people or an I disqualified based on answers I provided in another survey?

I had like 12 or more surveys I could take. Most of them points were low. I took 2 surveys and the rest were gone after that?

PS - Why are so many surveys the same questions? I've come to the realization that I love pumpkin spice, but hate being surveyed about it 5 times a day.