Well, they also promote people based on impact and, with rare exceptions, if you're holed up in a corner someplace you're probably not having a huge amount of impact.
If it was all about impact then ppl wouldn't be paying thousands of dollars to learn to play golf with their bosses. But you knew that already.
Reality is that the ones quietly holed up in the corner are usually doing all the unsexy maintenance-type work that the extroverts don't want to do (because it's not sexy).
Nobody cares about that work... until it doesn't get done. And so, nobody doing it gets promoted.