For example, you can email yourself an apk that of a program that was removed from Google Play and install it (I did this - developer decided it wasn't worth his time to support the app but was kind enough to send me the file).

To me that's an example of a power user - something that IOS does not allow.

To take it further - I imagine that one can't be a power user of an IOS no more than you can be a power user of a toaster - there is one way to insert and remove the bread, equally available to all.