Nonsense. I am an open source fan, but I also call it like it is. There are plenty of domains where closed source is still state of the art and open source options are at best inferior, sometimes laughably so. For example
- CAD/CAM
- Hardware design: simulation, formal verification, etc.
- Video editing (Blender's video sequence editor is so close to being good, but still has basic bugs unfortunately - hopefully in a few years I can take this off the list)
- Audio production, like Fruity Loops.
- Office software. Sorry but OpenOffice is still not a patch on MS Office. Last time I tried to use it for a presentation it literally reordered my bullet points. Absolutely bizarre bug.
And there's a whole host of highly domain specific software that open source will never replace because it's too niche, e.g. Simulink. I once worked on commercial software that solved for elastic wave modes in pipes. Good luck finding open source software to do that.