Wayfair Software Developer interview questions

The questions were not that hard. First a phone interview. That was good and professional, and got good feedback. So I was brought onsite. The onsite interview have 3 round. First two person ask about system design. both of the questions are easy and common. One of them is tinyurl. I start with using hash. And the interviewer does not ask me is there better solution. I know you could use database to generate Id than change to short url. But he keep asking me about hash value solution. I wanted to tell him there is better way. Anyway, Than one coding round. And a technique communication round. I believe I answered everyone correct. And taught several concept to the interviewer. But there feedback saying, I didn't give ultimate solution for tinyurl. I didn't mention the table modifier. I mean come on. The database question I nailed it. The interviewer keep asking scenarios. And I keep giving solutions. I feel like they are not looking for a engineer who can analysis different ways of solutions. instead looking for whether you have the exact same answer on the solution book.