Oh definitely - sorry, I didn't mean to be flippant or to suggest that dropping indexes on everything were some sort of magic scaling powder. I once worked on an app a client brought in from an outside company that had slapped indexes on every single column in the database (including longtext - it was Postgres). I've never seen something so broken.

But yeah. It's complicated. "Software is hard." But the best thing you can do is become aware of your ignorance, then try to eliminate what you can.