very true in thoery, ..but when it takes CIC almost a year to issue you a new PR card when its due for renewal - that can (and will) restrict your ability to travel.vasyok said:"They need to have the freedom of movement" - nothing stops those people from travelling. Residency obligation is not a restriction on your ability to travel, it's a part of the 'contract' between a person and Canada.
A colleague of mine wasn't able to visit her dying mother abroad as apparently CIC didn't issue her new PR card timely and "no" PRTD doesn't work, that too takes time and could cost someone his job - if you're abroad and unable to return here timely to resume your duties!