I think there's an easy "best of both worlds" take here: 1. The majority of the performance problem could've and probably should've been summarized as "you nee

I think there's an easy "best of both worlds" take here: 1. The majority of the performance problem could've and probably should've been summarized as "you need to use an index". (Maybe there were MySQL limitations that got in the way of indexing back then? But these days there aren't.) 2. Everyone makes mistakes! New programmers make mistakes like not knowing about indexes. Experienced programmers make mistakes like knowing a ton about everything and then teaching things in a weird order. All of these things are ok and normal and part of growing, and it's important that we treat each other kindly in the meantime.