RudderStack SDE-2 interview questions

There were 5 rounds of total where 5th was offer round. I was rejected after 4th round. All of 4 rounds went good. But then After 4th round I received the mail which blown my mind. Why did even they consider me for the interview and wasted themselves and my time if they didn't like my background. Interviewing here is waste of time. "We had a chance to review your background, and while we were impressed with your experience, unfortunately, we do not see a fit at this time for the SDE II - Backend role. "