You say that now, but Twitter also began as a way to send a quick message to your friends.

You used to be able to use it as a way to create a free self-managing SMS distribution list. Pretty cool, before I had phone with data capabilities.

That was even a use case I understood. Now I feel too old to understand how to use twitter. But that can't be it. Much older people seem to have no problem.

Umm it quickly pivoted to being a social networking site. Before they even were trying to scale they were a social network, micro blogging site.

But, it wasn't built to scale like WhatsApp.