The examples of IBM and Xerox were truly dominant in their day.
I'm not going to get into the definition of "monopoly" here. But there's a reason for the "No one ever got fired for buying IBM" quote, and there's a reason that "Xerox" is/was basically synonymous with "photocopy". No one calls an Android device an "iPhone".
Apple captures basically 100% of the market excitement and profit, but not sales or penetration. Apple is not dominant anywhere near what IBM and Xerox were.
So, for me this fails the test of ~"sales and marketing running the company and not bringing forward great new products". Apple is still delivering.
Apple is not all things to all people -- but no one is without choice. I think Apple, and Apple customers, are happy with Apple.
Anticompetitive market structure is bad for consumers loooong before it results in an actual literal "only one company in a broadly defined niche" monopoly.
You could argue I'm just saying they're high quality, which may be true, but the software has been degrading and I have no options if I value openness _and_ quality.
I can flip it and mention features that Apple products don't have that I like.
But this isn't actually an argument for monopoly. That just an argument that you like a company more then the other.
"It turns out the same thing can happen in technology companies that get monopolies, like IBM or Xerox. If you were a product person at IBM or Xerox, so you make a better copier or computer. So what? When you have monopoly market share, the company's not any more successful.
So the people that can make the company more successful are sales and marketing people, and they end up running the companies. And the product people get driven out of the decision making forums, and the companies forget what it means to make great products. The product sensibility and the product genius that brought them to that monopolistic position gets rotted out by people running these companies that have no conception of a good product versus a bad product.
They have no conception of the craftsmanship that's required to take a good idea and turn it into a good product. And they really have no feeling in their hearts, usually, about wanting to really help the customers."