Shirt and tie are actually fairly formal but there are certain roles or people who will ding you for not wearing suit. It is not very logical to ding people who wearing / not wearing blazer for interviews for office work, but it does happen.

So it is actually a fair question for fresh graduate to get a sense of what is appropriate.

For experienced hire . mid career, you can decide what you want to do. I had gone for interviews in smart casual (non-office wear) since my office has dress down dress code. Pretty sure there are some interviewers who are not too impressed with me not coming in blazer or even office wear at all, but I am not too bothered by it.