Engine replacement happens on airplanes fairly frequently. You don't want to scrap an airplane because of a single damaged turbine blade, or even keep it on the ground for longer.
It's rather: ... a competing formatter that may not be used on open-source projects.
The composition of both paints is a trade secret ("closed-source formatters"). The controversy is about disallowing the use on a broad class of projects benefitting the society.
No disrespect to Mr. Cook and his formidable achievements, but A LOT of the „value“ increase comes from the monetary policies in the zero interest rate economy.
On top of all other advice here: choose your learning material wisely. Ask the existing communities to point you to the best resources for your objective and skill level, then use those resources for a fast-track dive into the topic rather than wasting your time on less helpful material.