The logic is that people have always found ideas about the end of world, heaven, salvation, immortality, enticing. Singularity predicts analogs of these things

The logic is that people have always found ideas about the end of world, heaven, salvation, immortality, enticing. Singularity predicts analogs of these things in a manner that is compatible with atheism, so some atheists believe there will be singularity soon, for the same reasons some religious people believe the end of the world is near. I don't think that the above is good enough reason to dismiss the whole idea of singularity, but it is a good explanation why more people tend to predict singularity, instead of "viscosity" where improvements become harder and harder to do and AGI is needed to simply keep the same pace.