You're correct that people are hyperbolic in calling it a glorified iPhone. As you made the case, the iPad Pro is great for writing, research, emailing, art, photo and video editing...
yet Apple intentionally handicaps iPadOS so that the "last mile" of getting things done is just clunky and impeding enough, and that app developers are artificially limited in background processing and other "low hanging fruit" as Federico Viticci put it. It appears Apple is "weaponizing incompetence" to keep iPad Pro as a supplementary device.
ANSWER THIS QUESTION: Why is it that every device in the world, including Apple TV 4K, has multiple account login, but iPad Pro with the most advanced chip architecture in Apple's lineup can't have multiple accounts?
Is Apple "weaponizing incompetence" in the software domain, or does the iPad Pro have a hardware limitation that prevents multiple account login?