Nice try, but nope. Although Nintendo did publish VI DS and IX, they did not publish IV or V, SE did. Joker? Published by SE. Joker 2? Published by SE. Even then, Nintendo likely only published IX to guarantee exclusive rights, and VI because, well, VI had some issues getting localized. VI almost missed being localized yet again due to various problems. In the long run though, this is all SE unless Nintendo really wants the game. Nintendo can give a small push by offering to do distribution such as they did with Joker 2, but ultimately, most localizing decisions are being made by SE.

Nintendo gets credit where credit is due for VI, some credit for IX, although that one sold stupidly well in Japan and probably would have come west, regardless, but I can't give them credit for any of the other games except marginally so for Joker 2.

I was never giving them credit for IV or V. My post explicitly states "following IX." IX, then VI, then Joker 2 were all Nintendo published games. Since DQ IX we have not had an SE published game in the US.

Joker 2 was not Nintendo published. Nintendo distributed, but not Nintendo published. That basically means following IX, they got VI out of localization hell, and that's it.

Oh, you're correct. VGC had it listed as published under Nintendo in the US and when I searched it up Google said Nintendo was a publisher, but then looking further leads me to see that they were only distributors. Kinda odd.

Still, I don't believe in this mindset that you're putting forth from SE. They've never indicated that and there are some examples where it's not the case.

As I mentioned, it was my own conclusion that I came to based off the evidence I could find. The only major exceptions I can recall are:

Dragon Quest V and VI SNES, V because Enix didn't want to pay for high capacity carts, VI for the same reason and that it came out in Japan around the end of the SNES's life. There was the V remake for PS2 as well, and that one I'm not sure of. I guess based on how long they can take to localize DQ games, it just hit a point where they were considering it, but the PS3 was already on the horizon so they thought it wouldn't be viable. That and they may have had the DS remake in mind already by the time the V PS2 version was being considered. It's hard to say. There's the Wii Dragon Quest spinoff that actually did get localized unlike the previous examples, and I guess that was just trying to capitalize on the Wii's success. It kind of sold like crap even in Japan, so I'm surprised they thought it would do anything worthwhile in the rest of the world. Same deal with the Rocket Slime DS game. Super successful handheld, really not successful spinoff localized to try to profit anyways. The most recent oddity is the Dragon Quest Heroes game, but I guess they expect the more action oriented spinoff to have high western appeal as they try to build the Dragon Quest brand further.

There are a few other examples here or there from the GB days and such, but the past decade of Dragon Quest has otherwise pretty consistently followed the trend. If it ended up being a million+ seller in Japan, the rest of the world got it. If it failed to break that even by less than 50k like Terry's Wonderland 3D, suddenly it isn't a viable release for western audiences.

Technically we've gotten our fair share of ports of Dragon Quest games on iOS and Android devices. Those were easy to do though, so I'm not too surprised that they got localized. Drop in the same text, alter the control scheme, and either slightly enhance (or more than slightly unenhance as far as DQVIII goes) the graphics and boom, you've got a low effort title that will be all profit if it sells more than probably about 10k for the most advanced of the ports.