>In other words, I think there are actually humans who are usefully described as "alpha", but they are rare enough that most people will never actually meet one in their lifetimes.
Maybe not a full blown "alpha" (that would e.g. be their political leaders, CEOs, etc, so they will affect their lives, even if they don't get to meet one as a colleague/friend), but in most group scenarios there would be some people exerting much more influence than the others, even without a higher rank.
but in most group scenarios there would be some people exerting much more influence than the others
Sure, but that is what is meant by group dynamics. And it usually isn't one dimensional.
What I'm saying is that the alpha/beta modeling of this is lazy and misleading, and better avoided.
A very few politicians and a very few CEOs meet a useful definition of alpha, in my opinion. Your point about rank affecting influence is true, but I think irrelevant to my point.
Maybe not a full blown "alpha" (that would e.g. be their political leaders, CEOs, etc, so they will affect their lives, even if they don't get to meet one as a colleague/friend), but in most group scenarios there would be some people exerting much more influence than the others, even without a higher rank.