Absolutely!
There is no inherent reason all the computational power and storage we presently have in a laptop or desktop can’t be put into a phone.
As you say, the limiting factor is not the innards, it’s the input/output. Mouse/keyboard and screen.
I don’t want my laptop limited by the capacity of a phone battery. And make no mistake, the speed and storage on a phone are limited by the battery that powers it.
I want the most powerful phone that battery technology will allow but when I get home, I want the horse power that only a plug in the wall can support. And I don’t want an OS that is hamstrung but the limits of mobile technology.