The reasoning feels 'off' to me. They created a framework because the author wanted to be a leader, and because Meta's initial motivation was their ad manager... but those are philosophy/ideology reasons, not actual technical reasons. React is indeed complicated that is true, however other frameworks exist, which are also popular, and easier to work with, and to find answers for. I feel that's a pretty important factor - if you are spending your people time on building and maintaining a framework, that's time not being spent on other parts of the business.