Coming from a libertarian socialist perspective, I share your opinion that self-described anarcho-capitalists are not calling for anarchism as it is has been understood throughout much of history.
Understood by whom?
Tucker was an Anarchistic Socialist, but he understood "Anarchism" explicitly in terms that would include capitalistic anarchists.
When it came to definitions, Berkman and Goldman specifically and repeatedly defined "Anarchism" in terms of anti-statism. (They had another term, "free communism," that they used to describe their economic commitments.) They had some formulaic definitions that they repeatedly used as filler text both in <cite>Mother Earth</cite> and in <cite>The Blast</cite> (cf. "Anarchism" at the bottom of this page and "Free Communism" at the bottom of this one.)
Voltairine de Cleyre and Rosa Slobodinsky, in the 1890s, were willing to accept the label "capitalistic anarchist" for their own views, even if tongue in cheek and for the sake of argument, in debates with communist anarchists. Of course this is not really a fair description of their views, as the "Individualist" in the dialogue goes on to make very clear, but their attitude toward this kind of division of the field into terminological camps is telling, and refreshing: "Capitalistic Anarchism? Oh, yes, if you choose to call it so. Names are indifferent to me; I am not afraid of bugaboos. Let it be so, then, capitalistic Anarchism."
I wish contemporary anarchist scholars, with their chanted invocations of The Anarchist Tradition (whether broadly or narrowly construed), had more of that kind of attitude.
Even if it were true that the Tradition had a well-defined and uniform set of views on these issues, I think that would have absolutely no normative value at all, because Anarchism is a living ideal in thought and action, which is perfectly capable of new developments, radical turnarounds, new innovations, and new errors that have nothing at all to do with "anarchism as it has been understood throughout much of history." And thank goodness.
But in any case if we are going to talk about an our predecessors in an anarchist tradition, or about the historical meaning of the term, I think it's important to exercise at least some minimal sensitivity to how messy and internally divided that tradition always already was, and how far they may have differed with us, and differed among themselves, in what they saw as most important, most essential, or necessary, and who they would or would not recognize as fellow anarchists. This ground has always been contested, and to a great extent if we hope ever to understand what past writers have had to say about it, we need a healthy dose of de Cleyre's and Slobodinsky's good-humored flexibility in recognizing the ambiguity and contestation, and taking terms provisionally or for the sake of argument or communication, rather than trying to plant a black flag on them. But instead most of the contemporary writing on this subject has tended to project the writers' own priorities, and their own ideas about what's essential, onto their predecessors, and has had a lot more to do with trying to defend turf. (N.B.: Tucker's as guilty of that as anyone, in his attempts to "defend" Proudhon, Warren, et al. from the claims of the Communists.) This kind of anarchist classicism, like most forms of classicism, lectures monotonously about the wisdom of the ancients, quite as if nobody in the past ever argued amongst themselves about what "anarchism" meant, and as if it were some kind of intellectual property that the capitalists or the communists or whoever were trying to pirate away from its "traditional" owners.
This has tended to obscure a hell of a lot more about Anarchism, and about the debates of the past, than it has clarified.
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