The announcement comes after Twitter announced across-the-board job cuts earlier on Thursday, with plans to lay off 9 percent of its workforce, which equals about 350 people. The company also said in a letter to shareholders that it was going to prioritize some parts of its business, while deprioritizing others.

Source

Twitter was financially in a bad shape for a long time, the first year they generated some profit was 2018. Source Vine existed 2012-2017, I think they couldn't figure out how to monetize it. Twitter was a text based platform, tiktok was designed for video from conception.

But I still don't know why they didn't try to sell it instead of shutting it down.

Coub was also nearly shut down in 2022, it seems like it's hard to profitably maintain a short video service.

One more thing could have an important impact was music rights. Tiktok has special deals with record labels for background music, Coub was Russian, so they could just pirate music. Streaming wasn't big back than, only spotify existed, labels couldn't figure yet out how to milk internet users, so I guess Vine couldn't get as good deals as it would now. Too early, too legal.