(1.) that can be the case with any organization [and] (3.) we don't know how to quantify said organizations [and] (4.) the data we have is dwarfed by known Communist/Maoist groups worldwide.

That's kinda the premise of anarchist "organization" though. The idea isn't necessarily to quantify or delimit anarchists from non-anarchists via dedicated groups, but to operate on an individual basis and personal motives. It's a different form of participation and association with larger organizations. It may not hold true for every anarchist either.

(2.) it still doesn't make the argument that anarchist organizations are swelling in numbers

I'd argue anarchists are swelling in number not compared to socialist groups on a whole but rather in the number who support anarchist-inclined or anarchist-friendly groups rather than hiding in the woodwork. As you say it's not really realistic to quantify anarchists through groups. You gotta go via individual motives, which is a completely different metric, and probably leads many anarchists to adopt communist or socialist thought in addition to their anarchist thinking – which seems to be the case given the prevalence of anarcho-communists.

So now you're limiting Anarchist practice to the first world?

Admittedly, that was a bit of a half-arsed argument as – yes – it's rooted in the western world, which is where my personal experience is from (though it isn't an American perspective) and nothing I say runs contrary to your claims of:

the majority of the world's people and the vast majority of the proletariat exist in the periphery where awareness and acceptance of socialism are high.

Except that's my point. Even in countries where socialists are a major force, socialist movements are in no way homogeneous, but built on individual acceptance of certain parts of socialism. You're right saying anarchists are minority and that socialists have a broader support base (depending on country the numbers may vary, but my subjective estimate of 40% socialists more or less aligns with what you are saying). But even then, socialists aren't „huge swathes“ of any population I'm familiar with or have engaged with (this may be different in Asia and South America; I'm not familiar with those and can only look at the US, Europe, and the Middle East with any clarity). Instead, in countries with a socialist bent, it's invariably a solid core of – often politically engaged – socialists supported by a large number individuals & groups of varying ideologies, including a non-trivial number of anarchists.

Just because socialist programs are supported by so many people does not mean all those people are in fact socialists. Socialism draws a large crowd of sympathizers but, at least according to what I've observed, only about half of those who support their various causes also support the party in all its endeavors. They just identify with certain issues promoted by the socialists.

That's what I was getting at. I'm not arguing there are more anarchists. I'm arguing the socialist movement is supported by a larger number of non-socialists than socialists who actually follow the party program.

But I wouldn't recommend those groups "spontaneously organize", anymore than I would recommend to those facing down Hernán Cortés to do anything except swiftly and unmercifully driving him from your lands with the most organized force one can muster.

How do I argue this in any way? What I'm saying is that socialists at present don't draw a large enough crowd of pure socialists to be effective without outside support, even in countries where they're an accepted party or movement, and should be taking that reality into account. The issue here being that individualists (anarchist or otherwise) don't identify with all the party's ideas and socialists are loathe to accept support that isn't completely aligned with their program. While I understand the notion, this circumstance is weakening the socialist movement as a whole because staunch individualists are widespread in all but the poorest regions of the world.