Well, first off I wasn't presenting a "FOSS first" argument here. Onshape is a closed-source browser based CAD software but it works really well and I enjoy it. PrusaSlicer IS FOSS, but it is developed by the folks at Prusa who build the Prusa i3 printers - it is widely considered to be the "standard" for 3D printing slicers, better than CURA for sure.

Second off, this argument has an element of truth but kind of misses the plot. It is DEFINITELY possible for FOSS to be better and widely used and there are a couple of examples. I don't have a ton of time right now but just for fun I'll list a few. Blender is a great one, don't really need to explain how good it is. Also, KiCAD is really good these days too, second only to Altium. There are many more as well!