But I think that distinction was pretty moot when web 2.0 came along.
Imgur's entire purpose is clearly to host user generated content though, so you can't argue it's not "providing services".
Not at all. Imgur does the passive side too. And by number of operations, it is by far the biggest one.
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.