The solution to this is simple, Apple needs to make their browser usable enough that people don't go to extremes such as packaging entire browsers with their code. In many cases Safari's Javascript engine will even beat Chromium's engine.

Android allows any browser engine you like (even Webkit if someone would manage to compile it) and people don't generally do nonsense this on Android. I don't see why the situation would be any different here. The reason is simple: the web view API is easy to use, automatically updated, and backwards compatible.

As another benefit, devices that have fallen out of support may receive updates for browsers, making them usable again.