While undoubtedly there are many many humans that desire to socialize and be around other humans, there are many of us that find socialization less enjoyable.
So while I personally have benefited from periods of social interaction, I'd much rather be in isolation and self reflection.
Every time you buy something from Amazon, drink tap water, or live in a dwelling that you didn't build yourself, you are being a social creature. Few animals are capable of interacting in these highly complicated and choreographed ways.
I'd say that's stretching the definition of social beyond the breaking point. Technically those interactions involve other humans, but none that you engage with directly. It's direct human interaction that is the key to whether something is 'social' or not IMO.
Consider the context. The subject under discussion is those who want to be alone. It's quite possible to be alone whilst still enjoying the fruits of human collaboration.
It just crossed my mind that, as an hypothesis, may it be that introverts prefer to be alone because socializing is hard since we lack the necessary skills?!
But secondly, because the expression originally implied nothing of the sort, and still doesn't in biological jargon (which I believe is where it is/was most commonly used).
It was Aristotle who first used the expression "ζῷον πολιτικόν", and he used it to mean that humans exist in large ordered agglomerations as a matter of fact [0]. He also included bees and ants among the "political animals", but I don't think he ever said anything about any of them wanting company for it's own sake. And, at least in the beginning of his Politics, neither does he suggest that humans want it for it's own sake, either. Biologists, on the other hand, still use that expression with a meaning similar to that of Aristotle (animals who happen to live together), while including other groups [1].
Now, this wouldn't be a problem if in common language these expressions merely meant something else than what they do in biology, or what they mean in Aristotelian exegesis. That would be fine. But instead it seems as if the usage in common language relies on the usage in learned contexts to do a little bit of semantic sleight-of-hand, and suggest something else than what was originally meant e.g. "Humans have an inherent need for company: Biologists say we're 'social animals'".
Otherwise, the statement would have no authority behind it in common language. Instead, it would be just an unfounded assertion. In fact, that there are people who disagree with it already suggests that it is, at least, ill-founded. These are the people saying "No, we don't". But instead, readers are nudged by the usage in learned contexts to take it for granted, without further justification.
Either way, it's a bit like when someone conflates term "observer", as it is used in physics, with the term as it is used in common language to suggest that people can walk through walls if they wish hard enough.
[0] http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%...
If you try to change one aspect of your life, say being vegan, you find that the other aspects of your life conspire to pull you back. With valiant effort you can resist in some narrow sense... maybe not eating animal parts. But then you realize animal cruelty is inherent in almost all common forms of farming. And in order to participate in social activities you are expected to eat animal bits, and your doctor doesn't know how to support you.
And perhaps even more importantly, even if I succeed at meeting your requirement, say living in a separatist vegan commune, we will simply exist in a bubble until we burn up and disappear.
The way you have influence is not usually by taking an unflinching moralizing stance, but by pulling gently and incessantly on the rudder, steering your community almost imperceptibly towards a new place, making heart wrenching concessions, standing by as your values are desecrated in front of you, and getting up to do it again. To truly take a moral stance one must participate in the murky politics of the hive of human activity.
The absolutists just die. If not literally, then mythologically, because no one can understand their lives, and so no one learns from them... Except maybe a few accolytes who are trying to climb the same mountain of radicalism.
I've personally always been fascinated by the topic as I have met several hermit monks, have a friend who lived as one for half a year, and contemplated it for myself. The history of religious asceticism and hermits is quite interesting, and many of history's most famous philosophers/religious leaders/prophets were either hermits, or had periods of reclusion. And nearly every single religion has these hermit figures.
Anyhow, the downside is that being alone is tough. Physically and mentally. Humans are social creatures. However I have personally benefited from periods of isolation and reflection, even if I'd much rather be around others.