Except this is in fact bullshit since if you're ever working on some speed/memory critical code, that's the time to bother filling your brain with the different

Except this is in fact bullshit since if you're ever working on some speed/memory critical code, that's the time to bother filling your brain with the different options available and picking the appropriate one. Carrying around arbitrary knowledge to show off is pointless. Most code most programmers write won't ever run at sufficient scale or be sufficiently critical that CPU or memory bounds will matter, and using e.g. one sorting algorithm vs another will be largely irrelevant. It's recognising when you need to bother optimising that is the sign of a competent developer. And asking someone to write actual (not pseudo) code on paper/whiteboards - as I've seen in interviews - is like assessing someone's driving ability by asking them to mime driving a car.