Microsoft never got broken up so it certainly didn't teach us anything about breaking companies up not being useful. We'll never know what would've happened had they been. It might tell us that our laws are too weak, though.

Even if we reduce the story of Bell to "they got split up, then Southwestern Bell/Cingular/AT&T and Verizon gobbled up the rest of the others slowly" then we can see a big win: the n broken-up companies had varying levels of success because they tried different things and executed in different ways. That's a massive A/B test of the usefulness and efficiency of business practices that never would've happened if they'd never been broken up in the first place! And we'd have even less competition than our current wireless market if that breakup had never happened...

One interesting side-note I happened across recently was that Rockefeller's peak wealth was after Standard Oil was broken up. So what's the arguments against breaking up megacorps? We all know the value of competition, and we don't trust public companies to look much past the next quarter if left to their own devices, so why wouldn't we want more competition and less giant monoliths?

> One interesting side-note I happened across recently was that Rockefeller's peak wealth was after Standard Oil was broken up.

According to whom? And compared to what? According to what I read the man had (from memory) 24 million at the time of his death, which seems so bizarre. The problem is the accounting is not only difficult, but that the richer you are, the harder it is to account for all of it, and the more expensive it is to do so. It's not like a regular Joe who can just check his wallet or banking app. By the time you've audited your own wealth, as a billionaire, you've lost millions of dollars. The cost of accounting impacts accounting.