If the only embedded browser engine available, period, is Safari as provided by the OS, then it's much harder for app makers to introduce bugs (or features) tha

If the only embedded browser engine available, period, is Safari as provided by the OS, then it's much harder for app makers to introduce bugs (or features) that bypass Web content restrictions. Without the restriction app makers definitely would ship the equivalent of Electron apps—that is, apps embedding an entire browser engine, with the application built on top of it—to save a buck. [EDIT] and by Safari I mean Safari's webkit, of course. You can embed webviews! You can run JS! You can ship your own browser! You cannot ship your own browser engine, for a bunch of very good reasons, and I'm having a hard time in this case of thinking of any nefarious reasons for the rule. [EDIT EDIT] and then of course a browser engine is a giant attack surface. Better one version of one browser engine on your device than 20 versions of 3 browsers, most of which anyone but a turbonerd won't even realize are there because they're included with non-web-browser apps.