SQL queries related questions in SO are so full of redundant LEFT JOINs.

The reason why: People don't understand JOINs.

E.g. INNER JOIN is the simplest form of optimization....

*sigh*

Pretty much.

Thank you, I thought it was just me

I think people are stuck mantaining those horrible queries because "they were made by a senior who no longer works there".

I like to think the "senior" was just an intern at the time, scrambling a query together until he got the desired results and just said "Fuck it, it works."