I feel the same way as OP. I've finished more games on Switch since its launch than I have elsewhere in the past 2 years. I'm talking about good, single-player experiences.
I think there are several reasons for this. The first being that Nintendo focuses mainly on delivering good single-player games. The second reason is that the Switch hardware makes playing games fun again; being able to play wherever I am (most importantly, while I'm laying in bed) really allows me to get lost in the game since I can keep on playing. And seeing high-quality graphics on a handheld never gets old. The third is that the OS of the Switch has been designed to keep very little between you and playing your game. Especially since once you have a game loaded, you can lock your Switch and open it back up to the game right where you were before. Lastly, there has been an outstanding amount of quality indie games on the Switch eShop to supplement players' libraries in between releases of bigger titles. In my experience, these indies offer interesting single-player stories (reoccurring theme here) with unique gameplay mechanics wrapped up in shorter-yet-satisfying packages. And lastly, the Switch has allowed me to play local co-op with friends and family for the first time in a long time, thanks to its portability and its split Joy-Con functionality. I was out with a friend getting pizza awhile back, and we played Mario Kart while we waited. Just like the good old days.
