Second of all, you seem to be looking at things in very black and white terms. Of course you need to be able to communicate project requirements and dependencies and whatnot, both within and between teams. That's nowhere near the same thing as "networking" or "making connections" in the commonly-understood sense, which is much more about going over to have a chat and a laugh with Steve or Patty down the hall...or, to take it a step further, going out for a game of golf and running into the CTO there, and just happening to have a chat about your upcoming review.

So, in short: yes, of course "being good at your job" requires communication and people skills, as well as (in our case) coding skills. But there are many places where the skills required to advance—both financially and in your career—are exclusively the people skills, regardless of the fact that the skills that are primarily relevant to job performance are the coding skills. This creates perverse incentives, results in unqualified people getting managerial positions, and massively disadvantages those who genuinely care more about doing a good job than "selling themselves"—especially introverted people—in the workplace.