@JoshuaSlocum @charlie_root @p @mangeurdenuage @mischievoustomato Strong disagree.
"A bunch of servers" has no connotation of redundancy, fail-over, orchestration, a whole bunch of things we expect from "cloud vendors." See Amazon's S3, the first "cloud" offering as I remember. You put your data on it, with a limited full object API, they replicate it across multiple availability zones (miles apart, different flood plains as far as I know), it takes care of a lot of issues with persistent storage.
Your case is much stronger for something like Grok, but it's presumably built on top of many of the same techniques. Almost certainly not multiple sites yet, but that's completely impractical due to the costs and limited availability of GPUs at the moment. Xwitter by comparison has two datacenters far apart, each able to handle the whole load of the service(s).