Where as developing a PWA can be done on any hardware, and would be natively cross-platform. An offline PWA does not require an active connection, and in fact is the one of the reasons behind the idea of developing a PWA instead of a general webapp or website.
All other browsers allow the use of local storage to optimize and enhance your experience by allowing things like pre-loading data or storing your preferences. This disappears with the decision Apple made to clear storage.