Attempting to explain this irrefutable, unquestionable fact to a libertarian is like trying to explain sports to me: they ain't interested and can't understand.
They "get" this, but the actual goal is just to remove power from states and put it in the hands of individual property owners so that they are more free to exert it over people with less power.
Your average libertarian is poor, usually rural and not prosperous. They are generally just marks to the very few libertarians who would benefit from de-regulation and less government overisght.
Thinking more there is probably a great deal of overlap between the people who fit my definition of libertarianism and those who fit yours.
Today I would fully agree with you that the most experienced "libertarians" are actually conservatives dressed up in the clothing of freedom, but there's a sucker born every minute, and the key to bumping this particular sucker out of this particular ideology was not an accusation of crypto-conservatism (of which I heard plenty) but rather a frontal attack on the core ideas of libertarianism as I understood them.
On one hand demanding to be treated as if they are representing views in good faith when they are not is one of the most effective and exhausting strategies of the far right, libertarians included. So I try to identify it and refuse to.
But on the other hand yes, surely a lot of self-identified libertarians "on the ground" are being honest about their understanding and motivations, and it's shitty to dismiss their positions as disingenuous when they aren't.
I doubt it's possible to always get it right, and I'm not comfortable choosing one of those two errors to make exclusively. So I do my best and ask for forgiveness when I get it wrong.