This isn't about the Vita's theoretical sales in some parallel universe though. It's about the Switch's sales in real life. To claim they are solely due to portability is simply out of touch with reality.
Sorry I wasn't really disputing the reasons for Switch's success. I just added some sales for context. I just thought that the PS Vita's portability in Japan was understated.
I think it is fair that we agree on this statement though.
PS4 outsold the Vita in all countries due to games and other factors, but Vita had a stronger presence in Japan due to portability.