the opinion on the topic you are not informed about displays your values and having it might be beneficial to you.

And it might be detrimental to you just as easily. There's no way to know which without being informed, but an ignorant opinion based on "values" (aka vibes and what you want to be true rather than what is true) is more likely to hurt you or others in the long run. Just as being a racist bigot who has a wrong opinion about people of color might find that holding their racist opinion is immediately beneficial to themselves if they're in a similarly bigoted community, being a bigot is ultimately harmful for reasons I would hope wouldn't need to be explained.

An example would be a parent who doesn't want any gender-related issue to be discussed in the school.

Yet their uninformed opinion is harmful. Gender issues are inevitably part of our world and learning about them will not only prepare children to have an understanding of them that their ignorant parent lacks and help make the world safer and more livable for everyone as a result, but if that child themselves turns out to be gender stereotype non-conforming, then learning about those issues will help them better understand themselves and potentially save them from much of the misery inflicted on them by an ignorant populous.