There must be more to it than that. Left-handed people, RPG players and diabetics are also minorities, yet they are not hated.
Left-handed people were discriminated against at one time. In many places, they were forced to use their right hands instead for day to day tasks (this happened especially in schools). It has stopped now, for the most part, but it was once considered horrible (a sign of mental retardation, the devil's sign, etc).
Diabetics may not be hated, but that is more of a physical ailment. People tend to be a little more lenient on that.
As for RPG, many people were discriminated for playing them. At least in a person's school years, there were many cases of people getting beaten up for being a nerd, as they played RPG. It's not so much anymore since they are rising in popularity. But it's a little different anyway, as the games don't define the person. Unless they are fully emerged into them, and believe they are a wizard or what not, and then they do a get a lot of hate.
One big difference between the above and homosexuality though is that we now understand what causes diabetes, why people are left handed, and why people play RPG. But they were all hated at one time, or discriminated against.