"Well, what if a task needs to be done in the middle of some other task. You can't do that in a task loop untill you have finished with an ongoing task. Only after that you can attend the important or priority task ??"

Thats why interrupts were invented. All critical Tasks I have encountered could be divided in two the "must do now" and "can do later. Just think of serial communication, you must store in a buffer in a timely fashion, when you process the buffer is less important.

Erik