A non-trivial number of the "freelancers" on Upworks are in fact project managers for larger teams. They'll act as the face of the project and handle communications, but the work will be done by others.

But I agree it would be nice if this was made more explicit, and even touted as a feature. In many cases I might feel more comfortable hiring a team consisting of two developers a graphic designer and a UI/UX expert as opposed to one person claiming to be an expert in all those fields.