The query optimizer is pretty good at figuring it out for you. This is not true. Let's get back and compare the intellectual effort required to solve your task

The query optimizer is pretty good at figuring it out for you. This is not true. Let's get back and compare the intellectual effort required to solve your task in SQL and in my imaginary language. The difference in complexity is exactly the amount of effort by which you help the SQL query optimizer to do its work.