For clarification on this concept:
"It’s ironic that Social Media is so anti-social. It rewards persistence, self-aggrandizement, and talking about yourself all the time."
Of course, you're aware that blogging is one component of the broad universe of Social Media, but since this specific portion of the larger category is the primary example in your piece, I will focus on that as well, for this reply.
Given that the most successful bloggers (in terms of consistent audience) are neither solipsistic nor generally narcissistic, what evidence do you have that social media rewards self-aggrandizement and egocentrism? (No argument that it rewards persistence-- as is true of anything.)
Delusions of grandeur by a blogger usually lead to alienation of any appreciative audience, along with, paradoxically enough, increased scrutiny by detractors, and self-destruction.
Bloggers with large audiences are engaged in conversation on areas of interest to others. They create a space for an open give and take. In general, don't the majority of bloggers simply comment on things they are interested in, hoping their thoughts are read and discussed? And how is that anti-social?
Your analogy of an interrupting and egocentric partygoer depicts a boor, but even that behavior isn't necessarily "antisocial" in the psychological sense.
Further, the prevalence of the quest to be heard is not an innovation of interconnected computers. It is a cultural facet of a free society:
"Thought is not, like physical strength, dependent upon the number of its agents; nor can authors be counted like the troops that compose an army. On the contrary, the authority of a principle is often increased by the small number of men by whom it is expressed. The words of one strong-minded man addressed to the passions of a listening assembly have more power than the vociferations of a thousand orators...."
Alexis de Tocqueville, Democracy in America (ch. 11)
I suppose one could say that a blogger who attacks a famous celebrity is audacious, but that would be true of any writer at a magazine or newspaper in the egalitarian press. It is not self-aggrandizing to hold forth against the powers that be: it is distinctly democratic. And certainly not anti-social.