I think it is better to say JAX-RS requires you to use representations.
My Foo domain object has no idea that it is being used in a RESTful manner. It only knows of Bar (another aggregate root) and whatever entities it can navigate from via that Bar. In fact, I also have a command-line interface to this application that doesn't use REST or even HTTP.
My RESTful interface wraps Foo/Bar in to representations that link to each other via URIs. I guess you can call these DTOs, but if you (like stated in other answers) just annotate your domain model with what is required to marshal and unmarshal them then I think you're coding yourself in to a corner that prohibits HATEOAS.
This is also apparent when you have a collection. If Foo->*Bar are you going to return all of the Bar items in their unmarshalled form? Why not just a URI and maybe some other minimal data,
e.g.
GET foo/fff
<foo>
<link rel="self" uri="uri="foo/fff" />
<bar uri="bar/abc123">
<status="Active" />
</bar>
<bar uri="bar/qqq">
<status="Inactive" />
</bar>
</foo>
If the client wants to know more about a given Bar, it can
GET bar/abc123
<bar>
<link rel="self" uri="bar/abc123" />
<foo uri="foo/fff" />
<status>Active</status>
<title>Some Bar</title>
...
</bar>