The spyware one with the web browsers seems to be similiar to what I find with browsers in terms of “phoning home” and/or sending data to 3rd parties.
I didn’t really check anything else out, but it looks like when the articles provide empirical evidence, that it is reality 
Though, I CAN think of a few browsers they left out - maybe its a little dated I’m not sure.
If you’re reasonably technical or willing to learn - anyone can just do their own research. To say “secure” or “private” is a pretty big generalization when it comes to tech sooo…it depends what you are looking to protect against exactly as well 
Also it seems like for FF for example, they seemed to have tested only the current version at the time of writing soooo…but I guess, I mean you need at least FF v52 just to view youtube… but it is sorta interesting to see how FF has been evolving each release… O_o
The nice thing about these forums or any site that’s empirical - it really saves you the work if its already done by someone else 