I think we remember Vine through rose colored glasses. There was nothing on vine that was addicting, other than some very famous videos, that are still treated as relics. And everyone knew about those videos, because of how the feed was organized. TikTok is way more tailored-to-the-user.
IIRC people didn’t spend multiple hours a day on Vine. That was one of the reasons why it shut down — they couldn’t grab attention span of the aging users like Instagram and Snapchat did at that period (2012-2016). They also couldn’t get the fomo feeling that younger people nowadays get without TikTok et al.
7 seconds was great for certain types of videos especially quick comedic ones and brevity being the soul of wit means you have to be intentional with the little time you have
doubling the max duration length added greater versatility for creators while minimizing bloat.
making longer videos beyond a certain length can add to rambling and bloat which is why they've since added speed controls.
> There was nothing on vine that was addicting
Well that sounds like a selling point to me.