It’s because we could.
In life, there is a number of things which you don’t really want to pay attention to. Probably because it is not significant enough in your life. A tiny peck of dust. What we may think less important however, may be monumental to some.
In the case of sexual orientation, those who are unfortunate enough and know what they want, have no problems to be true to themselves. They are comfortable in their skins, out and proud. Nevertheless, there are some who know what they want but they can’t really be themselves too. This group of people probably ends up with the two extremes. One who is in utter denial in which they do not acknowledge them as a person with needs and the second one is those who afraid.