With that concept, one could/should simply set all the controls in a raw converter to default, render and move on in Photoshop?
Or shoot jpeg.
Sometimes as important as the resulting image is how streamline and efficient the workflow proceeds.
To me, although there may not be "much difference" in the final image ... there is a huge difference in workflow, time and drive space consumed whenever any adjustment or modification can take place in the RAW image processing pipeline.
While I am a fan of various plugins, I will almost always opt for doing everything I can in the RAW workflow and utilize an external plugin only as a last resort when that which I desire to achieve can't be accomplished in my RAW pipeline. Over the course of a year, the time I save and the storage space I can preserve for more RAW files rather than a mountain of tiff or psd can be a significant savings in both time and money.
What is worthy of pointing out ... we have been able to control fog/haze/smog in Lr from it's first introduction ... it just took more time, patience and certainly more than one slider to get there. There really was/is no need for an external plugin.