It still has that stigma because Nintendo reinforces it.

How so?

And all most of the titles they produce.

The third party support isn’t all family friendly or geared toward kids, but the same can’tbe said of Nintendo’s first party output.

Nobody says that Nintendo isn't also appealing to kids as well. But the Switch as a whole doesn't have the stigma of being something only for kids or geared towards kids. It's a console aimed at a wide audience that just so happens to have kid stuff too. 

Labo's just one series of games out of a library of nearly a thousand titles. The amount of impact something like Labo would have is negligible. 

Nintendo's games are aimed at wide audiences. Not simply kids and families. But also adults who like good games. There's a reason you see young adults playing Mario Kart in these commercials. 

There is probably a bit of that image clinging to the Switch, but I get the sense at least that most of that image has eroded, as the consoles has an extremely diverse lineup of games, many of which are considered "mature" or at least games that appeal to ALL ages. Though I suppose you're never going to completely wipe out the kiddie stigma if your company mascots include a cartoony Italian plumber hopping around shouting "yahoo!", a pink puffball, and a little green dinosaur, and you create games that look very colorful and Pixar-esque.

But if anything, I think overall the kiddie stigma has been replaced by the "casual" stigma mostly during the Wii era, which in turn has been mostly replaced during the Switch gen by simply being a handheld and therefore a "low brow" form of gaming or "not a true console." Though I don't think these views are widespread from where I sit anyway, and I'd still prefer that sentiment over "kiddie" and "casual" though.

When there's blood in Zelda as I'm slashing things with a sword, then I'd say they're over that image. As it is the top selling game on the system which doesn't kiddify combat visuals is either #10 or #11 as I'm not sure if Xenoblade 2 has blood but I do know Skyrim does.

Wii U actually supported the argument. It got a whole bunch of T & M rated 3rd party games in the first year and they all sold so bad that they stopped being released. After 2013, Wii U 3rd party retail support pretty much consisted of kid/family games.

Wii U stopped getting these type of games after about a year while Switch is ~1.5 years and is still getting games like Diablo, Warframe, Doom, Ark, Pillars of Eternity, Monster Hunter, Dark Souls, Valkyria Chronicles, Disgaea

Until they stop making family friendly Mario and Kirby games Nintendo will always be called kiddy.

They are a lot like Disney in some aspects. Think about how "mature Disney stuff" sounds to you now. Nintendo won't ever shake the deliberate family-friendly appeal IMO. To claim it is something that needs to be shaken, though, puts one in the mindset that games and gaming companies should be something else to be "better", no?

So kinda counterproductive to draw attention or make an issue of it really.