Anarchists are a genre of libertarians though. It's just that who dominates the landscape of "libertarian" is ancaps, who are just fascists with a weirder set of steps to implement a fascist nightmare.

Anarchists and Libertarian used to be synonymous, since Libertarian was a way to talk about Anarchism without being persecuted. Later in the US Proprietarians coopted the term Libertarian, and later even Anarchism by claiming to be 'Anarcho-Capitalists'.