I don't keep up with Vine enough to make any real historical claims but it seems like early coverage of musicians on Vine was all about mostly well-known acts doing things that simply contributed to their off-Vine brand.
In the last year Sean Mendes' discovery by major labels led to additional off-Vine development which set the stage for strong success with his initial EP release.
But what we're not seeing in the same way as we're seeing on more established sites like YouTube are the emergence of musicians like Lindsey Stirling and Peter Hollens. Both established themselves independently with YouTube as an initial base, releasing music and making money with digital tools and approaches that allowed them to make the choice of continuing independently or, in Hollens' case, signing to a major label.
So one of the biggest differences between Vine and YouTube is that you can monetize your presence on YouTube. Vine isn't built for that.
Vine Success Does Not Translate Easily
Nick Summers discusses two Vine musicians who've developed strong followings on Vine but have substantially smaller followings elsewhere.
Both 80Fitz and Eric Nakassa have 100's of thousands of followers on Vine yet, from what I saw of their social media accounts, that following hasn't translated well beyond Vine.
However in neither case do I see strong evidence that they're attempting to build beyond Vine so at most we could say that Vine success won't translate elsewhere on its own.
Using Vine to jumpstart a music career seems doable. People are getting attention for doing great things on Vine. And Nick Summers includes a few tips for creating better Vine videos.
But the reality is that you have to translate that success into longer forms on other venues.
Shawn Mendes is an interesting example of someone who was also posting cover songs on YouTube and since many have the stats available you see a sudden rise beginning in late 2013 and early 2014.
So though Mendes got his early attention on Vine, translating that into sales of his recent EP only came after he was also established elsewhere. And his manager said he found his Vine videos via YouTube videos. Not that he's lost that Vine audience but we're not still talking about him because he's a star on Vine.
Vine itself isn't designed to do much beyond Vine. Mini-profiles don't have links out. You can put a bunch of Vines together to make a YouTube video but it just doesn't have the same affect though aggregators are making some interesting moves with large compilations of Vines.
Vine does allow some people to express their creativity in a different way and gives them a chance to catch that initial flicker of attention. That's a powerful thing. But for most of those wishing more, the transition will not be an easy task.