That's....not even remotely true.
First of all, they are by definition not vertically integrated, because the same company doesn't create the hardware and the OS.
Second of all, have you actually compared the selection of hardware between Apple and any of these brands? I'll admit it's been a little while since I tried to give someone recommendations on a Windows machine, but the selection is just dizzying, and not in a helpful "here are all the different possible variables you could configure, and here are the possible values for them" way. They have (or, as I said, had) multiple different named lines within each product category, and several models within each line, and then each model has different possible configurations.
And unless you're the kind of person who has already studied the components enough to be able to build your own computer, you're not going to be able to easily tell, "Which of these actually has the most of the things I am looking for?"
Meanwhile, Apple's product lines aren't quite as simple as they once were, but they're still very straightforward. It's generally quite clear what the tradeoffs are when you're comparing between any give pair of devices in their lineup.