But their capital isn't idle. For the most part it consists of ownership via the stock market in large conglomerates that employ huge numbers of people and provide goods and services to significant portions of the planet.

That's why I don't see what good "dismantling" them does. Say someone offs Google tomorrow. The website dies and we're left with a bunch of people who have no job and some servers and buildings and whatnot that are less useful to anyone than when you started.