That may be true of some room assigners but I doubt you will find that approach consistently adhered-to. In the times we have used on-line check-in, we have found the instances of receiving our requests reduced dramatically. And I'm not talking about detailed, hard-to-meet requests. We typically ask for simple things like a high floor or particular section of Saratoga Springs.
Last fall the only request for BWV was to be as close as possible to Hollywood Studios. We used on-line check-in and the room was ready at 9am. However we were about 5 doors down from the elevators (which is pretty much the polar opposite of our request.)
I've heard from multiple sources that on-line check-ins are given priority assignments based upon arrival time. And that's consistent with the "room ready" assignment system Disney has largely been using for a decade now. Perhaps some CMs go the extra mile to try and match folks with their requests but I have yet to see any real evidence of it.
I still say that if the requests are important, skip on-line check-in and work directly with a front desk CM. It may take 10 minutes longer but if the view is that important, it will be time well spent.