I think they’re very happy to have the 2 parallel product lines; they might overlap a bit but who cares, business is about the numbers, not ideological purity of product lines.

The line they’ll probably never cross is that the Mac can run software in a (mostly) non sandboxed mode, with unrestricted background processes, which means it’ll always be the platform of choice for developers. Those extra restrictions on the iPad makes them more free to push it/experiment with it in the direction they wish (for better or worse, as we’ve seen with all the wonky windowing implementations, although the current one is mostly fine)

I love my iPad for drawing/photography, reading comics, and its extreme portability; I love my MacBook as a developer and as my main productivity machine.

Apple has no idea what the iPad is for but somehow they sell 20 million of them a year...

Apple has been very clear what the iPad is "supposed" to be. It is a touch screen computer. Between its form factor, touch first OS, built in camera, and possible cellular capabilities it can do a lot that a Mac can't do. Something as simple as walking around with it and handing it to someone like a clipboard opens up a million uses in the field that would be much more awkward with a traditional laptop. Artists drawing directly on the surface, musicians playing with touch controls, etc. all take advantage of how the iPad works.

If you insist on using programs and workflows designed for laptop computers the iPad will never make sense to you. I use AUM, Drambo, and a variety of other soft synths and effects on my iPad in conjunction with my analog synths. It's a very different experience than a regular computer.