Excel is ubiquitous because, as noted, it is an incredibly powerful tool. Facebook is ubiquitous because of network effects.
It's not a straight analogy. Specialized use cases can coexist with Facebook, otherwise half the Social-Network-for-X or Facebook-but-not-Facebook startups wouldn't exist. Productivity applications in contrast have an uphill battle and tend to stray away from anything even remotely resembling a spreadsheet UI.