This I agree with.They do it because it gives them more control over their products, rather than forcing them to make their software for standard hardware.
That is a nice utopian ideal to strive for if human motivations were benevolent, but most large tech companies seem to operate more sociopathically.The idea is that this leads to better performance while also reducing dependence on outside companies.
If they were selling a product to consumers, it seems less likely that it would be a processor or standard computer, and more likely that it would be a specialized portable device. Perhaps something along the lines of the Wacom Pen Computers, only built with a focus on running Adobe's Creative Cloud. It could simply be something for the server side of things though, seeing as their software is now based around an online subscription service with cloud storage.Or would it try to convince people to buy a processor specifically because they need Photoshop to run faster?