Threads, Facebook, Instagram and Whatsapp all went down today, because they are centralised services owned and run by Meta. When Meta breaks, Meta's services break too.

This doesn't happen on the Fediverse because it is thousands of totally independent servers owned and run by thousands of different people. If one server goes down, the other servers keep running.

This is one of the reasons why decentralisation is so important: it makes networks more resilient through diverse ownership.