The craziest thing I’ve ever asked a job candidate in an interview

“We’re in a pretty small office that has a drop ceiling in it. So there are a bunch of tiles and a few lights above our heads right now. Without looking up, can you estimate how many tiles are in the ceiling?”

It was the wrong question because the candidate was tempted to just look up (and by his response that was the reason the candidate was declined). Why not ask how many tiles there are in another room? Especially if the interviewer didn't care what the real answer/number is anyway? I think the candidate was right looking up and the question was a stupid setup.

The interviewer asked the candidate to follow a simple direction and the candidate chose to ignore it.

If he/she can't follow a simple direction during a job interview, that's probably a really good red flag they're not going to listen at other critical times. I say it's a brilliant check.

No, it's the same as asking people "don't think of an elephant".

It also has no similarity to tech support questions

Stupid question. Bad hiring process. You should not be in that position.

Maybe the candidate wasn't looking at the tiles. Perhaps they were rolling their eyes at the stupidity of the question. :-)