I'm all for striking the right balance with perf concerns, but in my experience that's not "just deal with it later". Giving no thought to performance is as bad as micro optimizing at the beginning.

It's not even an obsession. Those pieces of knowledge could be fully mastered in about a half hour. It's first principles knowledge, like chemistry or thermodynamics. I can tell in a minute that something like "Solar Freakin Roadways" is a scam, whereas so many people gave that scam literally millions of dollars. Knowledge is literally power, in a very concrete way that expresses itself directly as dollars!

Instead of having some basic first principles knowledge to spot such things ahead of time, benefiting from the collective experience of your field, you'd rather just labor in ignorance and run into everything for the first time and get out the profiler? Imagine scaling that up to the size of the Amazon or Google workforce?

I absolutely don't disagree with optimizing when it's obvious (two for loops instead of one, etc.) All I'm saying is that, when you have thousands of lines of code (millions?) and even more complicated/intricate connections in your head of different modules, all the while when trying to reach a deadline, things aren't as obvious. You have to make compromises, it's inevitable.

Amazon or Google did not scale up magically in one go by following established guidelines. I am very certain they had growing pains and I know that they had "hacks"[0] while figuring out the right solution for the problem at hand.

[0] As attested by a former Googler who works at my current workplace

What we disagree with, is the expansion of one's knowledge of what constitutes "obvious." Many people would say that the scam nature of "Solar Freakin Roadways" was far from obvious. Other people would smack their foreheads and ask why some people didn't pay attention in middle school and high school physics!