That's government's heavy hand in service to a specific political agenda, not validating the overwhelming will of the populace. The same could be said with lealizing hard drug and narcotic use legalizing prostitution. These involve more than just run-of-the-mill arbitrary policy choices, but part of the fabric of the culture as it exists in relation to religious beliefs, traditions, cumulative history, and even human biology. You can't just delineate all collective human experience into an arbitrary political arrangement and an undifferentiated mass of humanity in a vacuum. That is the chief problem with hypothetically "perfect" political systems as well as others such as language wherein the "perfect" international languages dsigned by lingusitic "experts" ie: Esperanto, Monoglottica,, and Interlingua, to mention a few fail. They lack an active base of popular support and fail to address the human culture to which they were to be applied. This is why communism, although once widespread through force, failed to gain loyalty and longevity.
Re government still being involved after being removed, I don't understand your point. What you are stating is a contradiction. e.g. libertarians want to remove government from these items and are therefore forcing government into the mix. This makes no sense.
By removing government from the drug war, for example, are you suggesting that government then promotes drugs?? Thats not the case. Private individuals and institutions would carry on the fight much more effectively and much less collateral damage. As for marriage, where does the government need to be involved other than enforcing contracts between individuals who freely agree to associate? Marriage is between individuals and their god, and its nobody elses business.
AS for the overwhelming will of the populace, we are not a democracy that relies on the will of the mob, but rather we are (supposed to be) a republic that protects the rights and freedoms of individuals. You seem to think the will of the masses makes right. But thats the same problem you complain about. This is where so many go wrong they think if only my party in all its nobility had the power
whereas libertarians promote eliminating said collectivized power and handing it back to individuals.