Can't make Facebook competitors on React?

Question

Facebook

Can't make Facebook competitors on React?
How then do Twitter and Instagram use it?
and Medium

Answer 1

Where did you even get it from?
React is distributed under the MIT license, which:
"permits persons who receive a copy of this software and related documentation (hereinafter referred to as the "Software") to use the Software without any restrictions, including the unrestricted right to use, copy, modify, merge publishing, distributing, sublicensing and/or selling copies of the Software, and to persons to whom the Software is provided"

Answer 2

Everything that is not forbidden is allowed. One of the principles of law.