provided they go to a good bee keeper (and I don't mean to be offensive by that, I just mean one that's not neglectful, or just hasn't done any homework). they have a better chance of surviving, I cannot remember the exact statistic so please correct me, but in the book Honey Bee Democracy, I believe something like 80 percent of the swarms in the wild do not survive the winter.
This morning I purchased a swarm from a couple that has 2 or 3 swarms come to their house every year or so, I was estatic I got quite a good bundle of bees for $50 with genetics that should be able to survive the winter. They got some money for their time, and aren't quite ready to get into BeeKing. I'm not sure how close that swarm was to choosing a nesting site, but the rain and snow that came in over the night would have surely made it a bit tougher at it, especially if the decided an overturned wheel barrow or the like was the perfect site, I'm sure the "landlord" would have kicked them out in a hurry.
Selling swarms I feel is beneficial for both bees and people as we like to let nature run its course, but often times it can lead to an unworkable situation (like a bear in a garbage can) Just my two cents, i'm open to correction and other view points, I know I'm not expert and do not want to represent myself as such.