No, but it does mean that you don't know about deferred script execution and possibly do not have a lot of experience in optimising page performance.
Perhaps, but as with any question like this, it's a foolish interviewer who draws such a broad conclusion from such a narrow data point. For example, as it happens I do know what <script defer> does, but that includes the fact that it can't be used reliably before IE10, which is why I've never actually used it on any production site. Not having encountered that particular functionality would therefore have made absolutely no difference to any project I have ever worked on, nor had any relevance to any senior people I was hiring to work on them with me.
Perhaps, but as with any question like this, it's a foolish interviewer who draws such a broad conclusion from such a narrow data point. For example, as it happens I do know what <script defer> does, but that includes the fact that it can't be used reliably before IE10, which is why I've never actually used it on any production site. Not having encountered that particular functionality would therefore have made absolutely no difference to any project I have ever worked on, nor had any relevance to any senior people I was hiring to work on them with me.