Here are examples of proprietary software that does nasty things beyond spying on users and restricting them.
Oracle's nonfree Java plug-in for browsers sneakily installs other annoying proprietary software.
That article disregards all other bad things about proprietary software. For instance, it regards the inclusion of proprietary Flash Player (which has a surveillance feature and DRM) in Chrome as a good thing. Chrome is a proprietary browser with a universal back door.
We don't agree with the article's views on those issues, but we present it as a factual reference.