Fair enough, it's horses for courses.
If the watch is serviced regularly the wear should be negligable. The earliest autos have been in continuous use since the 50s, those that have been looked after are in remarkable shape. They should it should survive for many many decades more continuous use, including use on a winder, provided they are cared for. Modern watch oils should mean the parts wear less now than ever!
If you only had two watches, I can see that a winder would make sense. The watch is only only off the wrist for 50% of it's life and may get worn a couple of times a week. Any wear caused by the winder is likely less than wear to the stem by winding at setting the time manually.
For the record, I don't have a winder. I must have 30 odd automatics. For me, the watches spend the overwhelming majority of their lives in the safe, not ticking. I don't have space for 30 winders and I agree that in my case the watches are better left dormant.
I guess my point is, if you're considering a winder, by definition you have a small collection and with the watch in very regular rotation. Keeping it wound will make b*gg*r all difference to the longevity. By the time your collection grows to the size that a watch spends 95%+ of it's time stored, owning a winder doesn't make a lot of sense.