STAFF+ INTERVIEWERS, WHAT ARE THE REASONS YOU REJECT SOMEONE IN A SYSTEM DESIGN INTERVIEW? (REDDIT THREAD)

Summary from the TLDR Web Dev newsletter

People are usually rejected in system design interviews due to their inability to analyze and articulate trade-offs in design decisions. They aren't able to explain their design choices clearly and justify the pros and cons of each. Other rejected candidates try too hard to find a single “perfect” solution or overengineer their solution.