When I interviewed for software development, I used to have a very open-ended question about optimizing a system I would describe, and there was no right answer

When I interviewed for software development, I used to have a very open-ended question about optimizing a system I would describe, and there was no right answer, there were tons of directions to go in, and the point was to get the interviewee to ask questions so I could figure out if they'd been around the block and which blocks they had been around. Why would you only want cookie-cutter "correct" answers to your questions? That doesn't tell you shit about the candidate?