This results from point #3. We do not want to depend on 3rd party in terms of content security and reliability
Not to be glib of course... but you mean like we depend on the commercial hosts/datacenters and top tier connectivity.
I do think this point needs stressing though... going your own way can be as bad/problematic as relying on a third party. Blindly choosing one or the other of these options is never a good idea :)
Tom