Earlier quoted context omitted.
Knowing the time complexity a given function you write is generally not important. However, the skill to analyze the complexity is an important one to have, because when performance issues to come up, it is often a very powerful tool to have.
Agreed. However it would probably be better to show someone some code with a loop in a loop and ask them why it could potentially be a problem. If they can tell you in Big O notation why its bad for large inputs then great, but so long as they can tell you why that's what really matters.
That is -- anytime you write a loop, you'd better think about what's inside it (and how long those things will take), and -- given the amount of data you might be sending through that loop -- if that's a problem or not.
I want someone to notice that they're making a remote call in a loop when it could be batched, cached, etc.. I don't want them to spend 2 days optimizing an algorithm tinkering with a bit of text that yes, is inefficient, but in practice is only going to take a few milliseconds anyway and isn't a hotspot.