Except the premordial soup theory is just speculation without any evidence to support it. Basically the chance of it occuring is about the same as if a tornado went through a junkyard and created a 747. This is because the basic building block of life, DNA, is as complex as a supercomputer. Therefore its virtually impossible that some premordial soup created life even once, let alone several times.
There certainly may be life on other planets, but they were created just like all life, by Intelligent Design.
I can't speak for anyone else, but for me, it's a simple matter of reasoning and logic, based on the factual evidence at hand (trillions upon trillions of stars and galaxies).
For the record, I'm not advocating that purely physical forces and elements accidentally triggered the formation of life (here, or anywhere else).
They are only seeing the smaller picture.
The Universe is the primordial soup. We are proof of that. We are made of stardust.