From what I can gleam, Vine simply had no way to monetize itself (something Twitter struggles with to this day, despite being the top 3 largest platforms), while Snapchat and Instagram could capitalize on that much more quickly as they implemented vine like features into their services.

And that just spelled the death toll. Why would a creator stay on one platform when the other is paying them? Consumers bemoan the constant bombardment of ads and now data tracking, but those are the costs of business if the user isn't directly paying a subscription (something services like Patreon and Onlyfans would take advantadge off around this same time that Vine was struggling. So Vine had potentially more than one way out). And if you don't/can't, some other billion dollar coporation will happily sell their soul for the trillionth time to outcompete.

These things live and die by the recommendation engine. Only fun I remember having with Vine was when someone would compile top 10 vines and put them on YouTube…

Twitter just doesn't know how to integrate products.