Homemade Sausage Making

I'm going to put up some Spanish Chorizo this weekend, so I've been researching recipes. I want to do a fermented, then dried version, but I'm curious why some recipes call for fermentation, but no culture. It seems to me that is maybe not quite as safe or predictable as using a culture, which, given the right conditions, should out compete any other organisms? I have T-SPX on hand, so I think that I'm going to use it, regardless of what a particular recipe says, but I was hoping someone might enlighten me on why some recipes include a culture and some don't even if they all have a fermentation step.

Example: Chorizo Asturiano https://www.meatsandsausages.com/sausag ... -asturiano

Thanks!

Rich