Allows for completely separate stacks running the status page, including DNS and registrar. In theory, you could run your status page using zero infrastructure common with your main domain.
Your answer makes no sense, DNS are decentralised!
If I recall correctly, it was their DNS servers that did that in a convoluted kind of way but not because of DNS as such. Due to some connection error or another the servers that also run DNS ordered the routers to withdraw the BGP routes to all Facebook properties which in turn killed access to said DNS servers.