The comparison between gaming computers and dedicated consoles didn't make much sense back in the 80s and 90s given the widely different input methods, software libraries and prices. It didn't make sense to compare them on the basis of "look, my computer can do all these things, what can your console do?" either.
Now, with the Switch vs. the iPad, it makes even less sense. Sure, on the surface, they're both tablets with mobile hardware in it, and they're both able to push 3D games. But that's like comparing a helicopter and a plane because they're both flying machines designed for transportation. Yeah, that's true, but you don't use them in the same situations. Helicopters aren't competing with planes because their respective capabilities make them suitable for very different jobs. Planes aren't competing with helicopters.
Cue someone linking to a study that shows helicopter sales are down due to planes or something :lol
The rise of mobile gaming on smartphones has certainly impacted sales of mobile gaming devices (DS+PSP vs 3DS+Vita). While for you it may seem like a plane vs a helicopter, for many other consumers these products occupy the same space.
The answer to the question "I want my kid to be able to play decent looking games while he's in the car" could be answered with 'iPad' or 'Nintendo' (especially since they will probably just install minecraft on it lol). iPad takes the edge here, with the ability to play youtube, Netflix, etc etc(other ways a child can be occupied). Likewise, someone looking for a pure home console may lean more heavily towards a more-powerful PS4, Xbox One, or even a PC.
These are all valid comparisons, because to many consumers, these are products in competing spaces fighting for their dollars. If the Switch can't be compared to a tablet, is it fair to compare it to Xbox One/PS4 (as a device that costs the same/more, has less power, fewer games, and less 3rd party support), or does that comparison not make sense either?