Why Nintendo should stay first party

[Mnementh]

Ka-pi96 said:

Mnementh said:
We can add to point five, that it isn't a given that games keep the quality if they go third-party, as illustrated by Sega. In fact, we cannot name one example of a game company going successfully from first- to third-party. We do for the other way - Nintendo produced a few games for other system before the NES.

NES was 3rd gen. Nintendo had a 1st gen console (the Nintendo Colour TV-Game), so are you saying Nintendo were 3rd party during the 2nd gen? As in... they went from being 1st party to 3rd party once already?

For instance was Mario Bros. released on Atari-machines:

Platform(s): Arcade, Famicom/NES, Commodore 64, Amstrad CPC, Apple II, Atari 2600, Atari 5200, Atari 7800, Virtual Console, Game Boy Advance (as secondary game in Super Mario Advance series), Nintendo GameCube (in Animal Crossing), ZX Spectrum, Game & Watch

http://en.wikipedia.org/wiki/Mario_Bros.

Also Donkey Kong, Donkey Kong Jr. and Popeye were released on non-Nintendo machines (I count Arcades as Nintendo-machines in that case).