When is it bad, exactly? And how does it pertain to this particular request?
I was talking more in general about 'more options are good', not about more options on this specific topic.
As for the question of when more options isn't good, it usually comes in the form of too many choices. Most people when confronted with too many choices will freeze up and go into inaction. Like how some people can't decide on what type of Android they want since they're too many choices and it's actually best to narrow it down to two or three options. This happened to my mom and even then we have to give her the simplest of smart phones with the least choices to keep things simple. So more options for her wasn't good.
Another is quality. For a quick and dirty example, a buffet has far more choices than one of Gordon Ramsay's restaurants which usually only gives you like two choices for a meal. However, Ramsay's food are far better than even a high-end buffet.
But how can it be bad in this case? I don't think it would take many resources to develop it or that the console wouldn't be able to handle that system. And what's more easy it's the fact that 3rd party games already created the achievements for Steam, PS4 and Xbox One, so it's not like developers have to create them for them to appear on Switch.
In this case I don't think that having the option would be negative. Nintendo don't have to do it in their games, but at least have the option for other games to have it when they already have that in Steam, PS4 and Xbox One.
Was talking about 'more options is good' in generation, not really in the context of this topic. Should have made that clear.
Also, it isn't about resources. Nintendo doesn't have a system wide achievement because they don't want it. To them, they think achievements should be game by game basic instead of a system wide requirement, so in game achievements are good enough for them. I don't see this really changes after avoiding achievements since the Wii.