Why can we not execute a stored procedure inside a function

Question

Why can we not execute a stored procedure inside a function?

Shakti Singh Dulawat · Answer

The rules of a function (no side effects no procedures) are so that the optimiser/execution engine is free to choose how many times the function will be executed without any concern about what could break if the function is called multiple times. When you do the openrowset hack if anything you call has side effects (changes data changes structure creates files etc) could create incorrect inconsistent results or even errors depending what happens behind the scenes.

Bhuvanesh Mohankumar · Answer

Function can do some set of operations however it does not have permission to execute the stored procedure i.e EXEC command cannot be executed in a function. Mark as answer if helpful.