It's not what I'd consider mission critical, but if you talk to therapists who have graduated in the last few years you'll definitely meet plenty who did a rotation where they are now working. I've also met several who got their first job as a new grad elsewhere and then migrated back to somewhere they did a rotation after a year or two. So doing your clinicals in a different town then where you wan't to live won't prevent you from finding a job, but I feel doing it where you are going to live makes getting that first job after graduation easier, and potentially gets some experience under your belt if the setting/city you want to end up in has a relatively lukewarm market for new grads.
I have talked to several hiring managers both from OP and hospital settings and they say they will always try to hire former students first before moving to other applicants, as it saves them time and money in the onboarding and training process to have someone who has essentially already worked for them. Maybe that is only the culture where I live, but I imagine it would be true elsewhere too.
If you do a rotation at a hospital/SNF/OP clinic that is part of a large corporation or chain I think that is of some benefit too after moving. If you apply for any jobs in the new city that are under the same parent company, you will have the advantage of already being familiar with their system. Again, maybe not a major game changer but not something to disregard either.