Edit 3: cancel this idea. I admit I need to come back with a better argument. I will come back to it the moment I see an example here on Voat where a user cries about an informative or artistic post not being marked NSFW because it doesn't filter their disney/reddit fragile emotional bubble.
This tag is used in particular social media sites such as eddit and Voat as a creeping censorship tool. The mere image of a gun, a spot of blood, a work of art showing a bare breast or even a fully clothed female, or the utterance of a "bad word" elicits a reaction to label content as "NSFW" thereby censoring content from everyone else. The world is not a disneyland resort, and it does a disservice to humanity to hide reality from each other.
No, my post doesn't have relation to the impending /r/watchpeopledie ban on eddit and the inevitable exodus of that group to Voat. I'm just tired of the "shield thine eyes from offense" ape mentality I see in social media.
On the positive side, just about every post I see on Voat qualifies as NSFW implicitly according to most normie standards, and I'm glad for that, and that's exactly why I continue to come here. But based on how it's used on other social media sites, I personally recognize the risk of the NSFW tag being abused as a censorship tool.
Edit: I admit it is kind of funny my post is auto-marked as "NSFW" given my title.
Edit 2: Disclaimer: this also follows my personal belief that under-age visitors not be allowed on Voat at all. Why? Just look to reddit for why.