There's some really high quality GNU software, like LibreOffice. Though, recently, when searching for a git client, I found it funny that some of the most frequently recommended git clients for Linux are proprietary, (GitKraken, Sublime) and that I couldn't find a GNU version that works as well as it's Windows counterpart.
I'm also not convinced the GNU license held up fully to it's promises, Android is also open source but took 50% of the mobile market. (And companies like Amazon [outside of Google] have used it for their own devices, like the Kindle)
What about ChromeOS?