It isn't consistent, because those portals are different things, and nothing says they have to be treated the same.
Youtube videos and Soundcloud stand-alone tracks are usually (in my experience) not intended by an artist as an official 'release'. If they are considered a 'proper' release by the artist, then it usually is in conjunction with a more 'official' channel to stream the release (usually with cover art + a label etc etc).
But I think the main reason for this delineation is that when I'm browsing an artist page, I don't want to see 100 videos and soundcloud tracks taking up the page, and I doubt other people do either. Or every fan uploaded video on the internet counting as a single + live + bootleg. For some reason if it's been 'released' onto Bandcamp, probably with cover art etc, it seems like a more specific release/ the artist intent is stronger.
Of course, there are always exceptions to the rule. No doubt if a single or a video doesn't fit into what I've surmised, it should be added differently. I don't think reosarevok is arguing that everything should be treated the same either.
But I honestly haven't seen this come up as an issue while editing and voting... I would love to see an example/s if we're going to discuss this at length, to be honest.
It would be a release.
But if he's just playing a song to people passing by (which I think is a more accurate metaphor for what we're talking about), it definitely wouldn't be... a stand-alone work perhaps
edit: if he's curated a special space that you walk into specifically to listen to that one song, and that's the only place you can listen to it, the maybe a release hehe