You are absolutely right. However, unfortunately there is always the same cycle of arguments when it comes to Nintendo consoles. It has been like this since at least the Gamecube days:

Past Nintendo console has failed: "Nintendo consoles don't sell, Nintendo MUST go third party. Their games don't matter anymore."

Nintendo's current console fails: "Nintendo NEEDS to go third party, otherwise they'll be doomed".

Nintendo console underperforms: "Nintendo SHOULD go third party" (add token "for the sake of the customers" or "if their next console fails" argument here).

Nintendo console sells decently: Basically silence. The console sells ok, but doesn't pose a threat other players in the market, so people don't care much.

Nintendo console is a Smash hit: "The console sells well, but third party games don't sell on Nintendo consoles!"

It's always the same circle, right now we're in "smash hit" territory and suddenly we have all these discussions about third party sales on Switch and how third parties just "can't" sell well on Switch or how it doesn't make sense for third parties to make Switch exclusives. It's been like that since the Gamecube - that's almost 20 years of the same circular arguments. Strangely enough, these arguments hardly get brought up with other consoles even though the PS3 had a bad launch, the PSP sold very small amounts of software (attach rate was below 1.0 in Japan for some time because of piracy), the Xbox One underperformed and the PS Vita flopped. (I'm not arguing we should bring these arguments up, by the way. Both Sony and Microsoft have the potential to sell a ton of hardware and software in each generation, just like Nintendo does).

Remarkably they're so far the only company to come back from such below par performances every other company that ran into that situation didn't survive long after from Atari, Sega and even Sony with Vita exited the portable market.

Actually i think the answer, for me, is yes. Maybe not "should" as the post asks, but i think id like them to. On one hand i vastly prefer a card based system over discs, but when the full game is rarely on the card it becomes a bit of a moot point. The rare AAA 3rd party game that does show up ends always being, for me, inferior and i dont care at all about playing handhelds. The only reason i buy 10do systems is for the 5 10do franchises im a fan of. But then the gamecube is the only system on which all 5 were present. If i could get all the games i love on 1 system that would be great.

This again?

I mean, really?

No.
We can't agree Nintendo should go third party.
They're one of the few companies constantly pushing the understanding of what an electronic entertainment platform should include in terms of input/output capabilities.

Look at phones. Without Steve Jobs to take them anywhere, smart phones are now cruising with the same configuration for the 13th year running.
10-finger touch, 1 screen, 1 mic, mono speaker, 1 front camera, 1 back camera, simple accelerometer/gyro. That's it.
Everything else is considered optional fluff. They can't even agree on whether or not to have a physical home button or a head-phone jack.

And talking about consoles. Microsoft and Sony seem content with not doing any single thing in this regard unless they absolutely have to. MS abandoned the Kinect after the tragic ONE launch. Sony has relegated the Move to existence in a weird PSVR add-on universe. None of it is mandatory, meaning none of it serves the developers in reaching the audiece, or serves the industry in standardizing technologies.

I personally couldn't stomach this industry without Nintendo's involvement in hardware development.

I understand that some people loves Nintendo franchises due to nostalgia and feel underwhelmed by the fact you need to pay hundreds of dollars in a console to play them along with a bunch of other games you don't give a damn

From a consumers perspective stand point it's really a nightmare, specially if you want 2-3 Nintendo Games and don't like the more casual direction of many Nintendo games since Wii. I suffered this on my 3DS, I barely played it besides the franchises I true liked

However not everyone shares this nuisance. I actually think that most people feel contemplated with the hardware and library of Nintendo consoles. Nintendo is a huge company and they bring something fresh to the industry, if they leave hardware market competition and buying options will decrease. The entry barrier for this market is huge and I don't see any company interested in filling the vacuum left by Nintendo

So it's better they don't go third party anytime soon

Should Apple start selling OSX for anyone to install on their PCs? Never.

It would be cool if they did, but it will never happen. It would dilute their brand power, and sales.

I think Nintendo should go third-party, yes. Frankly, I think it makes no sense that Mario cannot sell to 2/3 of gamers unless they shell out $200 to $300 for hardware.

I'm in a decent financial position, so I don't mind buying Nintendo hardware just to play 5-6 games per generation. But, I know lots of gamers that would love to play BotW, Kart, and the like, but aren't willing or able to spend the money on hardware just to play those few games. I suppose one could say the same about any exclusive franchise (Halo comes to mind as one that tons of gamers would play if was available on other platforms). But, really, the Mario universe is the most important in gaming, and would sell like Hotcakes on XB and PS.

Going third party is stupid. Anyone who suggests it is ignorant. It would not be as simple as all Nintendo series come to PS/XB The same thing that happened to SEGA would happen to Nintendo. A bulk of their IPs would no longer be made. Mario/Zelda/Pokemon would survive but Xenoblade is gone. No more publishing Bayonetta or Astral Chain. Luigis Mansion and Animal Crossing are probably gone. That's gone. Too expensive to publish on other platforms. SEGA stopped most of its classic franchises as they were just too expensive to make for 3-4 platforms. BOTW does not happen as a 3rd party publisher. Instead of BOTW, it would have been a much more traditional and conservative game in budget and scope. It would have a 2-year dev cycle, not a 5-year cycle.

Why should Nintendo be punished for being the only gaming hardware manufacturer that's capable of selling hardware on their own?

Tune in the next time Nintendo is down for the exact same thread!