I certainly helps but I wonder if those AAA ports are selling well. Because if not this third party support can vanish quickly.

It's a combination of first and 3rd party games, making Switch a success. But let's be clear. It's not brand new 3rd party AAA games that are making Switch a success. It's Indie games, and ports of older 3rd party AAA games. By older 3rd party AAA games I mean games that took around 2-3 years to go from being on PC/Xbox/PS4 to being ported on Switch.

It’s A reason, but not in the sense that you’d think.

The biggest reasons for the Switch’s success are as follows:
1) The Hybrid concept of the system has taken off and caught fire with the entire gaming audience. They love the idea of being able to have the choice between playing HD games on par with PlayStation and Xbox on TV or on the big go like a handheld. It also justifies why Nintendo’s hardware would be behind Sony’s and Microsoft’s: Would you rather have the version of the game that looks and runs the best? (PS/Xbox) Or the one you can take with you on the road? (Nintendo) It’s a better, more intriguing trade off than just pointless wiggle and gimmick controls just for the sake of having gimmick controls. Which was a problem that plagued a lot of the Wii’s 3rd party titles and even a few of their 1st party titles. The hybrid factor also offers strong potential in the legs/later years of Switch sales. Up until last September when the Switch Lite was released, the Switch was mostly sold as a console you can take with you on the go. Thus, it was mostly one system per household, which is mostly the case with consoles. And that was mostly due to the $300 price tag, which is standard for consoles. But for handhelds... That’s waaaay up there. So for the first 2 1/2 years they couldn’t really tap into the handheld market just yet. Now, with the Switch Lite and a lot of games arriving and coming that cater more towards handheld gamers like Pokémon and Animal Crossing, we’re starting to see a shift in the type of audience that’s buying the Switch. We’re shifting from ‘one per household’ to ‘one per person in the household’. As the years go on and the prices drop naturally to more handheld friendly levels. I feel we’ll really start to see this more into effect.

2) Incredibly strong 1st party library. Arguably the best library of 1st party games Nintendo has ever put out for one of their systems in terms of both quantity and quality. Breath of the Wild, Mario Odyssey, Smash Bros. Ultimate, Mario Kart 8 Deluxe, Mario Maker 2, Super Mario Party, Xenoblade 2, AC: New Horizons, Splatoon 2, FE: Three Houses, Luigi’s Mansion 3, Pokémon LGP/E, and even though I personally don’t like it, Sword/Shield. Even Ring Fit Adventure has proven to be a sleeper hit. Some stellar B-tier games collabs like Yoshi’s Crafted World, Kirby Star Allies, ARMS, Fire Emblem Warriors, Mario Tennis Aces, PM: The Origami King, most of the Wii U’s library that was ported over (Tropical Freeze, Captain Toad, Bayonetta 2, W101, NSMB U, Pokken DX), and some solid remasters/remakes (Link’s Awakening, Xenoblade 1). And we still have plenty of strong ones on the way: Breath of the Wild 2, Metroid Prime 4, at least one more 3D Mario game, at least one more Fire Emblem, Pokémon Gen 9, and a handful of other B-tier games like perhaps a 2nd Mario Party, 2nd Kirby or 2nd Yoshi game that will only add to the library. Or perhaps even some more new IPs like ARMS, Ring Fit, and Labo.

3) Third Party Support SPECIFICALLY CATERED TO THE SYSTEM. This is the big one. Yes, the Switch has a few 3rd party titles that are more traditional in the sense that they are readily available on PlayStation, Xbox, and other platforms such as PC and mobile: Minecraft, Fortnite, Overwatch, Rocket League, Crash, Sonic, Mega Man, FIFA, NBA 2K, etc. But those titles have very little to no effect on Switch sales compared to other 3rd party titles that are made particularly with the Switch in mind: Mario & Rabbids, Octopath Traveler, MUA 3, Astral Chain, Dragon Quest XI S, and soon SMT V, Bravely Default 2, No More Heroes 3, and Bayonetta 3.

4) Incredibly strong indie support.

Third Party Support is a factor. It just needs to be the RIGHT Third Party Support. The type that is designed and developed specifically to cater and take advantage of the Switch.

Not really but I think it is helping with consumer satisfaction and is making people more confident in adopting it.

No, I have never heard from anyone who bought the switch that they did it for the 3rd party games.
However.. I have heared quite often, that people dont buy the switch because it is lacking in 3rd party support.

I think its a combination of 1st and 3rd party games. Indie games are very popular on the console after all.

3rd parties did not start jumping on in the capacity they are now until after the Switch found success...so no.

3rd party is essential for all players in this field, if they want to stay competitive. The best thing is a solid combo of 1st and 3rd and the total sales show that pretty clearly. Microsoft is lacking in 1st party and are hustling to remedy that as we speak.
Having said that, I think portability is even more important for Nintendo than good 3rd party support. A pure home console Nintendo with crappy 3rd party would go the way of the Wii U.

Agree. The top 10 best-seller third party games on Switch should have been posted on the thread for us to get a better picture. At least we can make some calculations of the percentage of Switch owners who buy these games.

Agree. The top 10 best-seller third party games on Switch should have been posted on the thread for us to get a better picture. At least we can make some calculations of the percentage of Switch owners who buy these games.