Hypergrowth phases are temporary (eventually the entire mainstream is saturated), and the market share of various competitors, after hypergrowth ends, stays mostly fixed. Customers sign up with a particular product, and are reluctant to change. That's why, say, desktop PCs have run about the same set of OSes for a long time, the same word processors and spreadsheets have been popular in the same proportion for a long time, and the relative market shares between Coke and Pepsi or Colgate and Crest rarely change.