That holds mostly for either a) software that's made by software developers for software developers, and b) software that's utterly trivial. It's not true for most tools for professionals.

To name few examples - there's no decent alternative to Microsoft Office (free or otherwise), there're no decent open source alternatives to most CAD applications, to MATLAB (no, Octave doesn't count) & Simulink, LabVIEW, musical software, electronics design & manufacturing, etc. Essentially anywhere where the problem domain is nontrivial and the potential audience is limited.