No, it is an argument against anarchism. In a world where nation-states exist, anarchism simply doesn't allow for communites with enough cohesion and direction for adequate defense against more organized/authoritative systems. Even a nation-state with a limited government has more of a fighting chance. A community that cannot defend themselves lives only by the good will or benevolence of a stronger system. Lacking that, they are crushed by forms of governance that can fufill that basic need, and go beyond that.
I'd phrase it somewhat differently, I'd say such a society lives only to the extent that neighboring societies, or, more accurately, the cadre of elites that control them, don't feel threatened by it, or desire it's resources, and, then, initiate a fit of mass homicide.
This is, ultimately, an argument agains nation-states, because it highlights the corrosive effect of nationalism, and it's fundamental incompatibility with civilization. It divides people, on a completely arbitrary and irrational basis, into opposing camps. Those in the other camps, those outside the nation-state are, at best; naughty children, at worst; vermin to be exterminated. As long as this primitive tribalism holds sway, human progress is significantly limited.
It very well might be impossible for a large, more-or-less,... 'fully realized', shall we say, Anarchist society to coeexist alongside other nation-states. This is another point of divergence from Marxism, I don't make any definitive assertion, nor do I claim to be able to predict the future. I think it depends on the circumstances. At this time, however, one simply cannot, definitively, say. In the interim, I have suggested following the basic principles; identifying and dismantling institutions of oppression and exploitation, etc., etc.
If I believed world peace (or a world without primitive tribalism, as you say)...
I think it's a very accurate characterization.
was possible, I would probably be much closer to an anarchist myself...
Excellent.
On a serious note, my late grandfather once said to me that there are probably a great many people, who would never describe themselves as 'Anarchists', while not being particularly ideological, or approaching it in a systemic way, believe very much the same as I do. I think that's true.
I don't see that happening though...
Again; I don't claim to have any special knowledge, or powers of precognition.
-- and why would I? -- it certainly hasn't ever happened before, even before nation-states existed,
Before nation-states, there were kingdoms, and empires, of which the modern nation-state is a descendent. Before that, there were small, loosely organized tribes.
That something has not happened is not, by itself, necessarily, proof that it cannot happen. Also, this argument is a double-edged sword.
and people are all individuals with different personal motivations and drives.
Yes.
Call me cynical, but I envision a world without nation-states as a reversion back to feudalism or warlordism, at best; no amount of good intentions, education, technological progress will suddenly make humans entirely peaceful. We're not like that, as a whole. Some will want to be peaceful and work together without sparking injustice, and then some, inevitably, will not -- and they will ruin it for the rest of us, every time.
I don't find this cynical, myopic view of human nature remotely compelling. At the outset, we should be suspicious of it because it is the gospel of authoritarians everywhere, as it justifies their existence, as well as the monolithic institutions they control. That, alone, is reason for skepticism. Perhaps, more importantly, however, are the mountains of evidence to the contrary. This contention flies in the face of reality as you and I experience it. Not to mention all of the evidence from evolutionary psychology, etc.
Unfortunately, the worst representatives of humankind have oftentimes (not entirely surprisingly) have been the clerics, politicians, and generals.