From now on I'll explain #FOSS as "fully open source"
Words "free / libre" don't resonate with newcomers with no technical or legal background.
FSF About page uses the word "freedom" 67 times. Try reading it in non-English language.
Meanwhile many companies open source *parts* of code and use it as extra bonus. In reality some of them don't fully open source infrastructure or share other details, making it nontrivial for anyone to run the service on their own. That's open source. Not FOSS.