Thats basically saying:
"Nintendo makes consoles for themselves and dont care about 3rd party."
Nintendo see's themselves as software developers that make hardware.
No, what Veknoid_Outcast is saying is that Nintendo doesn't need to comply to the wishes of third parties who have no influence on Switch hardware sales. Nintendo isn't doing anything different to Sony or Microsoft, because those two don't design their consoles for third parties who are non-factors either.
Your assertion that Nintendo doesn't want competition on their hardware is demonstrably false, because Nintendo paid for Monster Hunter exclusivity, which back then was Japan's biggest third party IP as it had passed even Dragon Quest in popularity. Speaking of which, Nintendo got Dragon Quest on their consoles as well.
The catch is that lots of people have a hard time to accept that American and European AAA publishers aren't any more important than Japanese publishers for Nintendo hardware sales. Those people believed that the AAA industry decides which consoles succeed and which ones fail, so they doomed Switch in their predictions because Nintendo catered to consumers instead of the AAA industry. This thread is detached from reality, because it states in its title that Switch is in trouble at a time when its sales are considerably up year over year.
It's also concerning that we are on a sales and gaming website and about half of the people in this thread don't even know that there's a difference between carts and cards.