If you want to bring up the Nintendo 64, the 13 best selling games on the console were all Nintendo/Rare. Only 3 of the top 20 games weren't. Even beyond that, the majority were first party titles. I never considered the 64 a console for third party games. The console was also not great to work with for devs, and Nintendo were not forthcoming to them on how to utilize its power at a low level, so it was restrictive.
The Switch on the other hand won't be a pain for third party developers at all. It's probably the easiest Nintendo to develop for since the NES I'd say. It has a fairly stock Tegra ARM processor (CPU and GPU) like in standard tablets, uses standard graphics APIs, supports the Unreal engine and Unity engines, and has comparable power to a high end tablet. It's not an Android based device, but should be relatively comfortable to work with and port games to.
This is a huge step up from the Wii U, which had more obscure custom hardware, and was not popular with consumers due to not differentiating itself enough from the Wii to justify its higher price and causing customer confusion. I doubt third party support would have made enough difference to save it.