This is some creative re-interpretation of history.

"But the open PC hardware standard allowed Microsoft to develop an operating system that could run on any computer built to the PC hardware spec and they eventually unseated IBM, only to become a near monopoly themselves."

Microsoft didn't unseat IBM. IBM hired Microsoft to write its operating system, and Microsoft retained ownership of it, and many versions were made for many personal computers. Hooray, write it once, use it everywhere, right? But as more software began using direct calls to hardware (rather than just MS-DOS calls), that software had to be ported to new systems. Most were unable to port successfully, so everyone just started writing software for IBM PCs.

Even though there was this "open standard", the de-facto standard remained "IBM". All personal computer manufacturers were forced within a few years to abandon any proprietary product and sell only IBM PC-compatible machines. It took nearly a decade for the clone makers to reduce the price enough to make it affordable to buying something not IBM. Eventually IBM lost the lions' share of the personal computer market, and went back to its original near-monopoly of mainframes and minicomputers.

"But just as we were wringing our hands about what to do about Microsoft’s monopoly, an open source operating system (Linux), the internet protocols, and the free distribution of the world wide web undid that monopoly and we got Google, Facebook, Amazon, and other big tech platforms."

Microsoft's monopoly wasn't unseated, and the rest sounds like nonsense. There were a variety of operating systems and software running Internet services back then. Linux and the Apache web server unseated them from web hosting and commodity server needs, but Microsoft maintained its consumer-facing monopoly for... ever, and its business-facing network software. I don't know what "the internet protocols" has to do with M$... they tried to market competing protocols, they failed. We could extend this comment into the browser wars, but that's a whole 'nother rant (and the one monopoly they've really given up). As for "the free distribution of the www" ? What does this even mean? The web has always been paid for by somebody, I'm not sure who ever thought it was free. Microsoft was never a threat to the distribution model of the web - if anything, AOL was that threat.

Microsoft's tech platform is still here. Amazon, Google, and Facebook were not created after someone "unseated a monopoly". The web was just there, and these companies built businesses on top of it. Amazon and Google were even created whilst Microsoft was at the height of its power (1995 and 1998).

"And now we are wringing our hands about these near monopolies and their market power and the ability of bad actors to manipulate them. And around the same time, the technology to architect and scale a completely decentralized system emerges."

This is actually an interesting point, though completely by accident. It seems like new markets sometimes spring up while we're distracted looking at some other market. We're distracted right now with Facebook, Google, Amazon, etc. But probably some new business model will emerge that has nothing to do with these, and they'll become less important as we shift our attention somewhere else.

.... However, please note that we still use IBM PC-compatibles, we still use Microsoft platforms, and we will probably keep using Google Search & Maps and Amazon until the sun burns out.