Windows 10 actually fixed that problem. For the most part, apps can't change defaults silently anymore. The settings page for changing default apps has also been revamped, so it's a lot easier to use than in previous versions.

It would have been marvelous if Microsoft stopped right there. Instead, they chose to annoy users with an unskippable dialog box whenever a new app is installed that claims to know how to handle a PDF, JPG, or whatever. Fuck it, every app and their dog knows how to handle PDFs these days. I'm just waiting for the day when Windows suggests Slack as the default music player.