We all think our stories are fascinating and brilliant.
They can be if kept to a digestible length. However, our stories are rarely told with economy of words in mind.
The listener is either falling asleep or thinking about something else entirely if it goes longer than a minute.
One minute. That's all you get. Sixty seconds is actually quite a lot of time to convey information. Television and internet ads of that length seem long. It takes quite a lot of work to script those messages to make sure they are interesting, capture attention and convey the needed message in the allotted time.
Candidates interviewing for a job don't put in the same kind of work as a marketing person crafting an ad. In fact, the vast majority of candidates have never practiced what they want to say out loud even once. This includes high level executives.
If you don't prepare what you want to say and practice then your answers will be a rambling mess during an interview. It will take you 3-5 minutes to say what should have taken less than one.
While we think we are brilliant in our story telling, without practice the audience has a different opinion.