Isn't that the way it is done in both "systems"? You use webservices, you don't build in a mail-database of +7gig into a native app. Nor would you do that with the search engine or anything else. Whether it's a native or html-app, you are restricted to the devices resources either way.
I believe the discussion about native vs html-apps is more about the possibilities and toolsets you have instead of the power or responsiveness of the app (but I could be wrong)
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