Furthermore, suppose you're some company like, say, IBM which figured out some way to say, safely double the energy density and recharge cycles of Lithium Ion batteries, which you have patented. Let's also assume that you are shipping some critical problem which is dependent on React. Facebook could now freely use your patented idea, and violating it left, right, and center, and if you try to sue them for violating that patent, you're completely f*cked.

So Facebook's idea works fine if you believe that Patents as a Thing are bad (all patents, not just software patents), and should not be asserted under any circumstances, and it's fine for Facebook to arbitrarily violate any patent of any company who has become dependent on React.