I tend to mistrust the phrase 'obvious' because it is abused in the academic world, especially by mathematicians.
For one, if something is obvious, then it can be easily explained. But then there is the phrase 'intuitively obvious' which is a classic academic canard. The people using this tend to be dealing with a problem that isn't obvious at all, has many edge cases and is tedious to explain. So they call it 'intuitively obvious' and move on to something they would rather talk about.