Without user-generated content there is nothing to host. And in any case they long ago turned from an image hosting site into a social media site. There's reactions and commenting as a core part of the service now.

> Without user-generated content there is nothing to host.

So what? Without the passively-read content there'd be no user-generated content.

> There's reactions and commenting as a core part of the service now.

It is totally optional.