None of these companies should be proud of inventing narcissistic addictive UI elements, it's harmful to society. These companies are so narcissistic, that they want to fight over who gets credit for inventing these narcissistic addictive UI elements... the like button is not a genius invention, it's a simple idea that has been exploited for psychological addictions.
Also I believe infinite scrolling existed before FB, probably on RSS readers and other places on the web. NNTP clients did this long long ago.
If you're saying FB popularized them because they were so popular - well ok maybe.