When the Left question gender roles, and propose their demolition, all they are doing, is pushing for the destruction of the fundamental structures of society. Complying with the wishes of the Left, will lead to the destruction of society itself - which is the Left’s ultimate goal.

Think about it, displacing normal, time proven heterosexual gender roles, as well as relationships and nuclear families, with Feminism, LGBT education, and behaviors, will lead to:

1) A collapse of the population (since LGBT behaviors cannot produce offspring, and Feminism erects obstacles between men and women, keeping the two increasingly apart, minimizing the production of children).

2) An explosion of mental health diseases (since Feminism and LGBT ideologies and behaviors, are associated with elevated mental health issues.

E.g. per this article, “In the UK, young people referred for "gender treatment" has increased from 97 in 2009 to 2,510 in 2017-2018, an over 4,000 percent increase in 10 years.” 

In fact, LGBT behaviors are not only associated with elevated levels of mental illness: they have historically been categorized as manifestations of mental illness themselves.)

3) Extreme promiscuity, which in turn will lead to an explosion of dangerous venereal diseases, as well as the minimization of the formation of long lasting relationships.

4) The moral collapse of society. How exactly will this happen? The pursuit of heterosexual relationships is far more than the pursuit of sexual gratification. The pursuit of a heterosexual relationship is optimally about building a life together, with a natural partner. It is about accomplishing a great feat that involves self-sacrifice, long term commitment, and dedication to the welfare of your offspring. One benefit of this enterprise, is sexual gratification, that is in harmony with God and nature. By contrast, when people try to achieve pleasure directly, it leads to their diminishment. When the pursuit of pleasure overtakes someone’s life, it often leads to the person’s destruction. You see this in drug addiction, sex addiction, excessive eating, etc. Practically all of LGBT behaviors are about the pursuit of pleasure - which can mushroom rapidly into behaviors that are more and more unnatural and perverse. When this happens, LGBT practitioners no longer have much regard for natural boundaries and natural law in general. (The above is what the Apostle Paul in Romans 1:18-32 was talking about.)

Now a person who does not operate consistent with natural law, is usually considered by society to be immoral, and in significant cases, insane. When we tell the truth, keep our word, be kind to others, etc., we think and behave consistent with natural law.

Morality is behavior that is done consistent with natural law. When society broadly ignores natural law in its thinking and behavior, it becomes immoral. The consequences of this are that it loses cohesion, focus, and even sanity, and can be eliminated easily by its enemies.

Broad LGBT thinking and behavior in a society therefore form a gateway to the mass disregard of natural law, which in turn leads to people thinking and acting according to their own standards of ‘morality’ and ‘reality’. (The Left call this moral relativism.) Transgenderism is particularly dangerous, because it encourages society to outright disregard reality (the embodiment of natural law) and negotiate matters independently, which would lead to a  host of standards (of ‘morality’ and ‘reality’). This would in turn result in the loss of societal cohesion, sanity, and the ability for people to function as one, since virtually everyone would be thinking and behaving out of sync with one another - particularly in relation to natural law.