If your app used GC then everything your app links against or loads at runtime has to be GC-compatible. So Apple had to make all of it's frameworks GC-compatible. But many 3rd-party frameworks didn't.
Also: If your app used WebView to load a web site which contained something with flash (YouTube, ...) then your GC app would crash immediately because WebView loaded the Flash plugin which was not GC-compatible.
Thus using a WebView to load arbitrary sites was incompatible with GC.
If your app used GC then everything your app links against or loads at runtime has to be GC-compatible. So Apple had to make all of it's frameworks GC-compatible. But many 3rd-party frameworks didn't.
Also: If your app used WebView to load a web site which contained something with flash (YouTube, ...) then your GC app would crash immediately because WebView loaded the Flash plugin which was not GC-compatible.
Thus using a WebView to load arbitrary sites was incompatible with GC.