I have seen self-described “libertarians” even go so far as to oppose age of consent laws on sex as well as oppose laws against incest.
If no man may aggress against another; if, in short, everyone has the absolute right to be “free” from aggression, then this at once implies that the libertarian stands foursquare for what are generally known as “civil liberties”: the freedom to speak, publish, assemble, and to engage in such “victimless crimes” as pornography, sexual deviation, and prostitution (which the libertarian does not regard as “crimes” at all, since he defines a “crime” as violent invasion of someone else’s person or property). Furthermore, he regards conscription as slavery on a massive scale. And since war, especially modern war, entails the mass slaughter of civilians, the libertarian regards such conflicts as mass murder and therefore totally illegitimate. …Think such positions might grossly offend a conservative? especially a pro-family one that sees the so-called “victimless crimes” for the attack on the family that they are? Never mind the views on war that just do not jibe with George Washington’s notions of readiness for same.
I expect you'll see a lot more people calling themselves Republicans who couldn't even give you a decent definition of a republic without Google, support legislation that effecively destroys the boundaries between the state a national governments.
That's a ridiculous slur against a large number of people whose political views you apparently disagree with. Along the same vein, while you may have seen some "self-described libertarian" advocate for changes in those laws, I have read plenty of actual news reports of people who subscribe to the positions of the Republican and Democratic parties, and who vote for their candidates, be convicted of actually performing those illegal acts.
So if your logic were to prevail, we should doubly oppose the positions of Republicans and Democrats alike since some of them not only believe that such actions are appropriate, but do them.
Taking the most extreme position espoused by someone who claims to be affiliated with a political group as representative of the group is a tactic of the left, not conservatives.