Consoles get sold because of quality games. I would think someone would learn this just by being on the VGC forum for a while.
You'd also think that someone on VGC would be aware of history. After third-party support left Nintendo, their history has been extremely up and down. Because their games have been great one gen and then completely suck the next? That's unlikely. The Nintendo vanilla boxes have done poorly while the products with the biggest tilts away from traditional home gaming consoles have done much better. Do you think that's a coincidence? The Switch and Wii are examples of the console form factor being every bit as important as games when it comes to brand success.
(referring to bold) That is exactly what has happened on Nintendo home consoles. Nintendo first party games were far more popular on the Wii than they were on the Gamecube and Wii U. Wii Sports was an incredible hit. The Gamecube and Wii U didn't have any game that became a huge cultural phenomenon like Wii Sports. Not coincidentally, the Wii had a lot more third party games, including a lot more 1m+ sellers than the Gamecube or Wii U.
And that is how the Nintendo business model has always worked. They always rely on the strength of their first party games (or lack thereof) to sell hardware. During the NES and SNES era, Nintendo had very strong first party sales. This lead to a lot of third party titles on their platform. In fact the NES had even stronger first party sales than the SNES era, and the NES had even stronger third party support than SNES. Third party support on Nintendo consoles is essentially proportional to the strength of its first party sales. This has always been Nintendo's console strategy from the beginning: use first party games to drive hardware sales.
Sony, on the other hand, uses a different strategy. They try to attract extremely popular third party games, while also supplementing their library with good first party games. This model goes all the way back to the PS1. The PS1 didn't really start to take off in a big way until Final Fantasy 7 came out. This big third party title drove hardware sales, so much that Sony has decided to do what it can to attract big third party games ever since. That is the Sony business model: get the best third party games and supplement it with good first party games.
So when someone says that Sony first party games are on a Nintendo level, it has to be qualified. If you compare [Gamecube vs. PS2] or [Wii U vs. PS4], then you can say their third party libraries are comparable. Because that is what actually happens when their first party libraries are comparable: Nintendo gets clobbered. Sony third party is what matters most. But in most cases: NES/SNES, Wii, Switch, and every single Nintendo handheld, that is where Nintendo first party really shines. On those platforms their first party games sell like a big third party SKU. They sell like a GTA or CoD (or better). Sony first party is just not at this level. Franchises like GTA or CoD or Pokemon or 2D Mario are just on a much higher level than anything Sony can make.
Don't get me wrong. I think Sony makes good games. I think their first party line-up has always been a lot stronger (as a whole) than Microsoft's first party line-up. But in the same way Nintendo first party line-up is just much stronger than Sony's. And that's ok, because the two have very different strategies toward selling hardware.