Hmm, that may be part of it, and it's certainly a tempting thesis, but I don't know if it's accurate. It suggests that if you can just make a good enough film, and/or get people to give short films another chance, they'd realize what they're missing and watch & share it. And even if you've made the world's greatest short film, and people don't watch it, it's not your fault - it's all those people making crap screwing it up for you.
The problem is I don't think it reflects how people view things online accurately. There's a few ways you can discover a short film...
The first is searching for it. The problem is most people don't specifically seek out short films. They do seek out information about their interests, and when they do that they often find videos that are focused on that interest - which biases discovery towards non-fiction, topical material.
The second is through recommendations from friends, via social media, email, whatever - this is viral discovery. But before their friends can share it with them, they have to discover it themselves (see above). Once they have discovered it, they have to feel that it's something their friends would be interested in enough to share it. Again, this biases sharing towards topical material - people likely have circles of friends that are into the same topics they are, so they're likely to share material that covers those topics because they know it will be of interest.
I think this is why the most successful short narrative projects tend to be fan films or web series - they're tapping into a more specific interest than just a generic genre. People watch them because they're fans of a particular character, or video game, etc - not because they're looking for a short form of entertainment. Some of them aren't even particularly good, but they still get a lot of views - because they satisfy a particular topical interest, much the same way non-fiction videos do.