Why did you not respond to my comment "the more time dependent a task is the worse a URTOS will be"? which dircetly opposed your statement?

Forgive my ignorance but what is a URTOS? I am not familiar with the term. Do you mean Universal?
no, the product you describe is an UnReal Time Operating System.

and the cooperative RTOS where each rasks runs to completion there is no stack overhead and hence has faster task switching.
THAT is not called task switching by others than those that can only think URTOS, that is simlpy called "the workloop" and the calls are called subroutines NOT tasks.

I do not say anybody must use an RTOS. Only that it is a tool to be used when appropriate.
That is perfectly correct, just you that think of it as "first choice" I think of it as "last choice".

Again, if time is of no importance, a URTOS can be a good choice.

In a small embedded system such as the '51 type (I know a 1MB code cellphone is called embedded, - been there, done that - but that is a totally different story) there should be only ONE task: Get the job done. It can be beneficial to divide that task into subroutines, but there still should be only one task.

Erik