Yes.
Some people blindly accept as true what the religion their parents have told them is true w/o even looking into the belief system they claim to follow. In other words, some people don't even know what their own religion teaches.
People that blindly follow one belief system w/o looking into the possibility that another may be true could be "selling themselves short" as you say.
Even if you were brought up to believe in one in particular as true, studying other ones can strengthen your faith that your initial belief system is the truth.