Yes. This 1000x. I hate it at work when I come across code that was written 3 years ago that has literally no traces of why it's there and a quick summary of what it does. Especially because that code is always the most abbreviated spaghetti you've ever seen. People should stop thinking (their) code documents itself because 99.999% of programmers cannot do it right.

I really like the Google way of coding: assume the person reading the code is the most 1337 programmer ever, BUT that this person knows absolutely nothing about the project

This is something a lot of people don't seem to understand. Even if code is self-explanatory, I want to know why it was designed that way.

I've fixed bugs where the fix was only a one line change, but it was extremely difficult to figure out, so I left a 10ish line comment above it explaining why it has to be done that way.

Yeah, just 15 seconds and jot down a comment. Whenever I’m even hesitant, I just leave a comment. Doesn’t hurt anything and it can always be removed if not needed

Easier to remove later rather than add it after the fact

If done right, the "what it does" is in the method name. If your method is too complicated to summarize in its name, chances are good you should split it up or extract parts of it.

Hard disagree - that's just dumb:

// Calculates tax
function calculateTax() { }