The argument has never made sense, systems like NES, SNES, GB & DS had amazing 3rd party support yet Nintendo's 1st party offerings were by far the biggest sellers.

The only reason to buy a nintendo system is if you like most of their exclusives. Cuttently the only game that could make me interested in buying a Switch is Zelda. But it is not worth to buy a system just for one game.

This statement is false as portability plays a huge factor.  Just recently I get to play...

Starlink

Dragonball FighterZ

Ys VIII

Valkeria Chronicles 4

Wolfenstein  2

South Park

Crash n Sane

Warframe

etc

All of these games are great games that I would have a hard time finding the opportunity to play if not for the Switch.  Dragon Quest XI and Mortal Kombat 11 will join those ranks as well.  So yeah, there is plenty of reason to buy a Switch for many people outside of just Nintendo games as the games I listed are only a few of the most recent and do not even come close to the entire library of full retail games available on the Switch.

Nintendo in recent years has created an environment in which it can thrive. By choosing less powerful hardware and offering something unique that separates themselves from what Sony and Microsoft are doing, they are able to play to their strengths. First party titles are polished and almost always a lot of fun. They have a baked in fan base that will buy most of these AAA first party titles.

While they miss out on some of the high end multiplats, they still get a decent share of them. Between first party, some third party, indies, and retro, they have once again carved out a nice market for themselves. They are different enough that many owners of a gaming PC, PS4, or Xbox One would be happy to also have a Switch. Couple that with the diehard Nintendo fans and it a recipe for success.

Back in the NES days, third parties actually did extremely well on the NES, especially if you break it down by region. For example Dragon Quest would sell the best Nintendo game in Japan and Ninja Turtles would sell like the best Nintendo game in the US.

Problem is that third parties don't want to be tied for the best. Rockstar likes that Sony has to kiss their ass. That makes things easier for Rockstar (or EA or Activision or whoever). But whenever Nintendo makes the best selling console, the third party games come anyway. Really it's better for the consumer that way. For me the best console was the NES, because it had all the best third party and first party games on the same system.

This is something that alot of people glance over, just because it's not getting all of the AAA 3rd party titles does not mean 3rd party support is bad. It actually has really strong support of small-medium sized titles.

Indies-Celeste, Owlboy, Hollow Knight, Dead Cells, Overcooked, Stardew Valley, Rocket League, Steamworld Dig, Moonlighter, Undertale, Axiom Verge

Japanese titles-Monster Hunter Generations, Valkyria Chronicles 4, Ys VIII, Shining Resonance, Dragon Quest Builders, SNK Heroines, Warriors Orochi 4, Disgaea 5, Octopath Traveler

Free-to-play-Fortnite, Paladins, Fallout Shelter, Arena of Valor, Warframe, Smite

Previous gen ports/remasters-LA Noire, Skyrim, Payday 2, Dark Souls, Diablo III, Okami HD, Resident Evil Revelations 1+2, South Park: Stick of Truth

Retro compilations-Mega Man/Mega Man X Legacy Collections, Street Fighter 30th Anniversary, Sega Genesis Classics, Atari Flashback, SNK Collection, Namco Museum, Arcade Archives

Kid/Family titles-Lego Incredibles, Lego DC Villians, Minecraft, Nickelodeon Kart Racers, Just Dance, Hasbro Game Night, Crash N Sane Trilogy, Carnival Games, Go Vacation, Starlink

Current gen ports-Doom/Doom Eternal, Wolfenstein II, Ark: Survival Evolved, Civilization VI, Dragon Ball FighterZ, Mortal Kombat XI, Mega Man 11, South Park: Fractured But Whole, Outlast 1+2, FIFA, NBA 2K

None of these games are individual system sellers but collectively they give the system a well rounded lineup and are great support titles to Nintendo's 1st party offerings.

Nintendo user base seems so salty at the moment, I do not think I have seen a saltier user base.

Not my problem when gamers restrict themselves to one platform.

Care to elaborate?

I think at best the lack of competition affects Nintendo's pricing model, since with as many big games as PS4 - Switch users might have a haed time choosing how to buy AAA titles. But even I'm not sure about that. Nintendo titles do not sell more because they have less competition.