As ekklesiagora says, I don't think It is merely ideological. It is not purely ideological that DOMA had to be overturned some years back, to allow gay marriage. It's a harmful oppression that harms gay people and classifies their love as unwanted and lesser than others.

When people talk about how being gay is immoral and make laws that either make life harder for gay people or treating them worse than heterosexual people, they're harming those that are harming no one else. It's like people saying "omg, people having crewcut/long hair/etc is immoral, so disgusting, so let's not let them marry anyone else". In other word, it's perfectly fine for people to say that X isn't for me, but when that opinion is used to create laws, regulations, social oppression, bullying behaviors, etc, that right to free speech has turned into bigotry and discriminative behavior that harm people that are just being themselves and not harming others. In fact, it's an oppression over the free speech and self-autonomy of others.

Psychological coercion, bullying, classism, libel, etc can be as harmful as physical violence.

Again, there's a very important distinction between people saying that they feel being gay isn't for them and that they're not into the idea of being gay, and externally judging/harming others by saying/asserting/etc that gay people are terrible sinful people that should feel ashamed and kept out of businesses/services/etc.

ps: We live in an imperfect world. There are often several goals/ideologies that interfere with each other that we can only approximate those goals as best as we can. Anarchism is a great goal, as much as equality of opportunity, social welfare, societal growth, increasing everyone's happiness, etc. For example, while living in capitalism, most people do not have the privilege to opt out to survive or function without participating in the system. Naturally, that doesn't mean that we cannot behave in somewhat anarchistic ways even while/when we're not participating in the system. Most people do in some respect.