Maybe this has been said already, but one major problem with Twitter is that by default, the average person will publish and share content on it that's a complete waste of time and of no value to anybody.

The average unit of content shared by a user on Instagram or Snapchat is vastly more entertaining and relevant, and I think they achieve that by being more visual. Those platforms are image- and video-first, and they have all kinds of image and video filters. If we gave those tools to a monkey, it would produce something worth sharing.

The quality of their content is enforced inherently by the tools they provide you to share with.

Facebook achieves the same in a different way, by tightly integrating with your identity and social circles.

Twitter doesn't have any form of inherent quality control. Tweets are just words with little context. The people tweeting are usually strangers.