No, you’re right, it is not about a single iOS-like feature hampering "pro user functionality". It is the amalgam effect of Apple’s efforts of catering to the iPhone user, or the average Mac user, that alienates pro users. If you look at headline features for Yosemite, El Capitan, and Sierra, there is not a single "pro user" feature there, but plenty for your average Joe.
In short: the pro user segment is alienated by Apple’s seemingly indifferent attitude towards them, and the increased integration, or synergy, of iOS with macOS does not help in any way. Generally, pro and power users want flexibility, options, customizability.
Apple seems hell bent on removing choice. Pro users were alienated when they removed firewire connectivity, you need adapters and dongles for just about everything now, and it’s not like this will be remedied with the 2016 MBP is it? Then there is the sad thing that is Mac Pro... That is how Apple actually forced a lot of pro users onto hackintosh systems, as unbelievable as that sounds, but you can run a hackintosh and have a better, more flexible, more performant, macOS experience, than with the real Mac Pro...
In short: the pro user segment is alienated by Apple’s seemingly indifferent attitude towards them, and the increased integration, or synergy, of iOS with macOS does not help in any way. Generally, pro and power users want flexibility, options, customizability.
Apple seems hell bent on removing choice. Pro users were alienated when they removed firewire connectivity, you need adapters and dongles for just about everything now, and it’s not like this will be remedied with the 2016 MBP is it? Then there is the sad thing that is Mac Pro... That is how Apple actually forced a lot of pro users onto hackintosh systems, as unbelievable as that sounds, but you can run a hackintosh and have a better, more flexible, more performant, macOS experience, than with the real Mac Pro...