It was specifically fbstatic-b-a.akamaihd.net which was also not responsive, preventing css & js to load rendering a completely broken page on my browser.

Akamai has several different networks, one for streaming media, one for regular http, and one for https. They also have an S3-like storage system and a DNS service. Some customers are configured with several of these offerings at once, so it's hard to know which, if any, experienced problems and led to the outages.

Honestly, I doubt it was an Akamai issue. If Akamai experienced network problems, dozens or hundreds of sites would be affected. If an Akamai config issue (ie human error) were to blame, then it would probably only affect one site, not several. Neither FB nor Akamai is dumb enough to push multiple site changes at once.