Re: Why ?
There are different forms of restriction. An Apple user might feel restricted at not being able to run software not obtained through the App Store. This was especially evident before Apple allowed 3rd party keyboards on the App Store. An Android user - as I am - might feel restricted because some of the better third-party productivity software is only made for iOS and not Android. Similarly, some third party hardware is only made to work with iPhones / iPads. After several years, I might feel that my supply of software updates has been restricted as well.
I think its important to look at restriction as a principal, vs how it impacts a workflow in practice. I suspect a great many people's actual workflows aren't impeeded by Apple's artificial restrictions.