I don't think people say that in a literal sense.
It's the same when people say that X console doesn't have games... They are trying to make a point.
In this case, i think that when people say that (Pachter also said it before) it's in the sense that Nintendo users only care about Nintendo games and the rest doesn't matter.
Why? Because Nintendo has a ton of meaningful IPs and they sell from good to amazing. Not just that, it feels like Nintendo fans are more open to new Nintendo franchises than new or old IPs from 3rd parties.
When people look at Nintendo's top 10s for their consoles, the majority is Nintendo titles (new or old).
Sadly, 3rd parties not only come in second place, but there are times where they come in a distant second.