I think it's more that the landscape has evolved. When systems that needed to exchange information were maintained by enterprises, SOAP made sense (and still does, if you ask some of my ex-colleagues).

When web development became accessible to the masses and the number of fast-moving resource-strapped startups boomed, apps and websites needed to integrate data from 3rd parties they had no prior relationship/interaction with, and a lighter and looser mechanism won -- REST (ish), without client/server transactional contracts and without XML, using formats and constructs people already knew (JSON, HTTP verbs).