You can disable it all, with a little work. Some stuff doesn't work afterwards however it is all stuff that was never present in Win7 anyway. Personally, I have the diagnostics/telemetry turned off and also have Windows Update set to fully manual on my main desktop and laptop, for example.
I'm not sure actually if it tracks stuff outside of UWP. It looks like the "over 100 million users" is from CNN, not from Microsoft. So it might be based on some other information source than tracking or anything like that.
Now regardless I fully understand their desire for telemetry information- Heck I added telemetry information/logging to the stuff we make- but like you mention Dave that only tracked information regarding our Applications, and we use it for tracking what features/components actually get used, how often, and also can look at it when things go poorly by matching up timestamps with error info. I don't like that I have to strongly assert that I don't want to have information traced, logged, and fired off to their servers, though I can see why as the harder and more technologically inclined a user needs to be the more information they are going to receive about how their software is used.
On the desktop and laptop I use primarily, I disabled the Diagnostics and Telemetry services/capability via group policy editor as well as by disabling a few services, along with adjustments like making Windows Update 100% manually handled (I have to start it myself).
That article you linked is sensationalist drivel, though; it's from 2 years ago and is very inaccurate. For example it refers to the tracking of questions you type into Cortana as a keylogger and says it applies systemwide. They did not do any research or investigation; that feature can be turned off in the privacy settings and only applied to certain Cortana interaction components.