The truth is somewhere in the middle, and it depends on what you want. Everyone and their brother wants an upper floor theme park view, and of course there just aren't that many of those. So, it is easier for the front desk to flatly refuse to consider it as there is no way to make those folks happy otherwise.
Regular owners and guests can't make advance requests, but VIP owners with enough "qualified points" can reserve specific rooms in advance. This is another reason why the front desk is hesitant to move people; they can't easily tell which reservations are pre-assigned to VIP owners and which are not, and moving VIP owners out of their assigned rooms used to be a big problem here.
Other requests that are easier to meet may well be possible. But, I would not assume that you'll get a request, no matter what it is or how easy it seems like it should be to grant it. For example, if the prior poster literally could not stay there if above the 5th floor, I'd try to book somewhere else. Just because they've always made it work in the past doesn't mean you'll be 100% certain to get it from now on.