I made many of the same points recently (albeit in a cheesy Facebook post -- https://www.facebook.com/alex.feinberg/posts/101002165710317...), but I had a different take on this: I saw this as a hearkening to Valley's original values as opposed to a media-fueled distortion of them that doesn't quite correspond to on-the-ground reality.

Full disclosure: I worked at Facebook and am still holding on to some stock. I also worked on a project ("Panama") with Acton at Yahoo and knew the reputation of others involved in WhatsApp like Rick Reed. Rick Reed built a high performance messaging bus in C++ at Yahoo that was the foundation of much of Yahoo infra outside of search, so the use of Erlang was not a surprise for me. Nonetheless, I'm sure my opinion would be the same even if I never worked at FB or Yahoo and didn't know of anyone involved.

Keep in mind that while I know nothing of Brian's rejection from FB (it happened before my time), but "Facebook has good talent" is not mutually exclusive with "Facebook rejected some really great people". It's also very likely that he was going for a more senior/leadership position and interviewing engineering leadership is an even more of a dubious "science" than interviewing individual contributors.