For some it's understandable though; Minecraft is a classic. Stardew Valley, Hollow Knight are Nintendo games but far better.
But I think a huge factor is that it's the ONLY dedicated portable gaming system out there at the moment, with a huge market penetration. I mean sure, many people have phones, but phone controllers are uncommon and docking stations for the TV even moreso.
And with those controls, I can imagine it's easier to port a game to the switch than to a phone (even if things like the CPU are comparable to phone hardware).
Anyway, that said, come to think of it, the Switch only has a handful of top games / system sellers; I can think of BotW of course, Smash Brothers, and Mario Kart (which they could / should have done a lot more with if you ask me). Probably generic mario game #1573574564 as well, idk what it's called, it's more of the same.