But why didn't those users just go to mastodon?
Ideologically motivated (i.e. "federated-first") open source projects never succeed in attracting mainstream users. They have to make too many compromises, and inevitably prioritize their motivation (federation) over what is necessary to attract the mainstream (e.g. excellent UX).
The fact that mastadon is doing as well as it is, is sign number 1 that the market is begging for something like threads to happen.
Here is a common thing that happens to me:
- someone sends me a funny post
- I want to "like" it or save it or whatever
On Twitter and other centralized social media this is very easy to do. On Mastodon, it is not. I have to copy the URL, paste it into a text field on my instance, and then like it.