I also think 30 seconds is just long enough to tell a meaningful story rather than Vine's 6 seconds which was only useful for short-form comedy.

And note it's 60 seconds, so even more so

The music licenses are a big deal - you can put actual popular music in your tiktoks and not have to worry about it being taken down.

Is the 30 Second rule applicable World Wide? Just wondering.

I haven't tried it but everybody says TikTok's magic ingredient is the AI behind recommendations.

Vine launched in 2012. There probably wasn't a critical mass of mobile phone owners, specifically teens, at that time. The iPhone hit the market only five years earlier.

Better recommendation engine

Or actual people doing the recommendation?

You are right to a degree. Vine at its peak had less than 30 engineers total and at most 1 person working on the "engine".

Think also about how much data plans and smartphones cost in 2012, particularly ones centred around video streaming