I don't think it's an unfair assessment to say that they prefer not to acquire developers in most cases. It doesn't mean that they will never ever acquire other devs but we haven't really seen them go out of their way to expand through M&As the way other large companies do. They have maintained partnerships over several decades with companies like IS, HAL, SRD etc. Any other corporation would have bought these smaller companies a long long time ago. I'm not saying this is a bad thing but NLG's owners selling feels like the classic example of Nintendo's hand being forced or risk losing a valuable partner. The fact that the impetus came from NLG rather than Nintendo is crucial imo.
Other companies expand via IP acquisition as much as anything else (see example: the MS Bethesda acquisition), Nintendo hasn't done that and don't see them going that way. But even Sony operates in similar ways to Nintendo in this regard: every studio they've acquired is one that they have a long development partnership history with (Sucker Punch, Insomniac, Naughty Dog, etc.) and likely wanted the acquisition to happen.
At this point, IS, HAL and SRD are so intertwined in Nintendo's business almost from the very beginning (right down to some of them operating in Nintendo's offices for a period of time) that they're practically inseparable. Were that to ever change, expect a chequebook to come out. Until then, it's practically wasted money for no material benefit to the company; they're not just literally getting the milk for free without owning the cow, the cow itself is serving it up to them. Other companies in a similar scenario would buy them up because of paranoia and feelings of insecurity, but it seems to me Nintendo feels pretty damn secure about the status quo with regard to those 3 independent entities not breaking out of their orbit.
The Next Level situation seems to me like Nintendo had the talent on board for
8 years, but were waiting out the majority owners being ready to sell; while some of the majority owners involved in the day-to-day were clearly happy with the arrangement (Jason Carr in particular), there might have been hesitations from the others that needed resolving. That we knew nothing until the deal was already effectively done tells me that the majority stakeholders knew Nintendo was interested and they could have already put in an offer before then that was declined at the time; put another way, they were willing to sell
knowing Nintendo would buy and it didn't appear they shopped around a sale to any other entity and most of the major stakeholders still work there (were I a betting man, I'd bet they sold their stake for an equivalent value of Nintendo shares, which would appreciate over time). That the deal only took 2 months to close also lends some credence to that.
It's not that they're "averse" to acquisition, they just have prerequisite conditions that must be met before such a thing will be entertained, or the investment (talent and expertise) runs a major risk of being for nothing. That's not aversion, that's prudence, and there's a difference.
And they have other creative methods of acquiring talent, like acquisitions-that-aren't-technically-acquisitions (see example: the NdCube restructuring to house a whack-load of unemployed Hudson Soft staff in Hokkaido) or some gentle poaching (see example: Hidemaro Fujibayashi, BotW director, whom they lightly enticed to leave Capcom/Flagship of his own choosing).
But that prudence can sometimes mean that they end up walking away from what looks like golden opportunities to those of us not in the know, giving the appearance of reticence toward M&As.
Everyone likes to bring up AlphaDream as an example of how Nintendo doesn't do acquisitions, but we don't have any indication that their ownership were at all receptive to that, which is one of Nintendo's pre-conditions for an M&A. And by the time it would have been receptive to it (read: when they were already deeply in debt), as awful as this sounds, it would have been cheaper to give employment contracts to the unemployed than it would have been to pay down AlphaDream's near-500 million yen in debt, while also allowing them to negotiate case-by-case with each employee.
Also, let's look at MercurySteam. The talent there seems to gush about working with Nintendo to the press (one pre-condition down), but the talent's opinion of the management team, on the other hand....
The seemingly simple solution would be to buy out current minority stakeholder Nordisk Games and majority stakeholder/giant pricksicle Enric Alvarez to resolve the management crisis, keep the talent happy and keep them making (what looks likely to be) record-selling Metroid games, among other things. But if either Nordisk and/or Alvarez are unwilling to part with their stake in the company, Nintendo has not met all their pre-conditions for acquisition and will either have to abandon the company for the exposure of its downright toxic work environment as they bleed out quality staff, or will have to consider... NdCube-like alternative options.
In either case, the prudent method of M&A Nintendo practices can sometimes lead to heartbreaking circumstances and furthers a false consideration of their business practices.