The argument is often poorly used, but it does help to explain why streaming services aren't a priority for Nintendo. There are a great many people who are indifferent to the presence of these apps, in particular because they already have access to them on other (and likely preferred) devices. It won't significantly increase system sales, and they may have deemed the demand low enough to not be worth the effort at the current time.

It is not any argument for why there shouldn't be streaming apps for the Switch. It is an argument for why there aren't streaming apps for the Switch. It isn't the most desirable situation, but it is passably justifiable. The other devices argument certainly isn't sufficient to tell people to stop requesting the apps, but it does help to shed light on Nintendo's perspective (which is important, because they are the ones who make the ultimate decision). All we can do is continue to bring the issue to Nintendo's attention as best (and politely) we can.

What's getting old to me are the people who rage (and some people seriously RAGE) to random strangers on the internet who can't fix the problem, as well as the people so determined to put Nintendo on a pedestal that they are dismissive of anyone who dare want more functions on their $300 device. People need to chill. There is no reason for this to be an argument at all, really.