@FireFly
Definitely. It might be that the lower the layer, the more general.
I'm not 100% certain that's exactly true. Maybe it is for services as
opposed to particular technologies. Remember token ring? FDDI?

Examples of (centralised) broad portfolios of web services might be
those operated by Google and Amazon. They are fairly diversified.

They also operate lower layer infrastructure which they rent out.

I think this means that they are more robust than Twitter as entities.