"Why isn't there a successful company building and maintaining a suite of common alternative desktop applications?"

Sure there are but in other domains than "office".

For example CAD has few incumbent companies with their portfolios - Autodesk, Trimble, Nemetchek, Bentley. (etc)

For design - Adobe, Affinity (well it's all Canva now), then legion of smaller offerings like Clip Studio Paint.

CAD is the only domain in which I have domain knowledge but I would be surprised if there are no others.