They launched Alyx exclusively, which didn't do much for SteamVR.

In any case your argument is genuinely confused. You yourself estimated the value of Nintendo exclusives at the Wii U's sales level, so if 13 million people will go to Nintendo to get their exclusives no matter what, then you still have to explain 90% of the Switch sales, because people really seemed fine with skipping Mario Kart 8 when it was stuck in a potato. On the Switch it is one of the biggest games of this generation... despite being a last-gen game. Ditto for Breath of the Wild.

Not that it matters. Obviously the two devices that provide the exact same function with a lot of the same games and comparable non-overlapping releases are comparable. An argument that they aren't is either pushing or suffering from some sort of aggressive bias, but I'm increasingly unclear on what bias you're even dealing with here, because none of the piecemeal arguments you're making seem to make any sort of concerted case in favor of... anything.

Look, ultimately the point is that the Deck is a very successful handheld PC, but still a handheld PC, and still relatively niche compared to consoles and very niche compared to the kickstarter of the entire hybrid handheld space. Yes, you can compare the performance of gaming devices against each other and yes, that does recontextualize the success of the Deck. That's all fairly common sense and we can skip relitigating it because the whole "but they have Mario!" thing is a borderline non-sequitur.