"their own apps" + "the best apps from their competitors" minus "their own apps" does not correspond to a single competitor's offerings - which is Apple's advan

"their own apps" + "the best apps from their competitors" minus "their own apps" does not correspond to a single competitor's offerings - which is Apple's advantage, according to Mossberg's logic. His argument's got little to do with Apple's own apps (not that they have particularly much of a presence either - even on their own devices.)