You can say this about pretty much any outage or mistake ever. Every single security vulnerability or jailbreak too. How could the entire computing industry with 10000s of amazing people have missed Spectre/Meltdown? In 2018, Spectre affected basically every computer system ever - desktops & mobiles, AMD/Intel/ARM and it was basically open to exploitation since speculative execution which is decades. 1000s of employees is not as big as it sounds given how much FB does and hindsight is 20/20..