Because the former is not a prerequisite of the latter. In fact, at that level of education, it would be readily acceptable in academia for one to challenge the prevailing theories. Science, in fact, is predicated on scientists doing just that -- challenging the current science with non-acceptance as that is how knowledge is furthered and expanded.
By the way, "not accepting" something isn't the same as rejecting it. "Not accepting" something merely means that you find the evidence isn't enough to convince you, which means you don't know whether or not it's true, not that you think it's false. Science, truth, these things spring from those who claim to not know, not from those who claim to.