MacOS had more screen sizes to target in 2011 than the iPad does today; in any case, Apple has always tolerated having iPad apps that are blown-up phone apps. Mouse support for iPad apps has existed as an accessibility feature before it was deemed a core feature. Even that isn't any kind of technological leap, mouse support has been part of Android for at least 15 years now.

None of these really explain the sloppiness and unfocused nature of Apple software, which has been best-in-class until recently.