So every application will have its own set of proprietary device drivers? This is beyond ridiculous.....
Do you want to use a general purpose OS with a easily coded app to do a specific time critical job, or do you want to invest the time in developing an optimized, integrated OS and app to perform a specific time critical job in high volume?
The latter is the way we used to implement imbedded real time control systems and they were extremely efficient in the use of the extremely limited hardware resources available at the time (~ 30 yr ago).