It does seem like you have a valid point there. Unlike rail passes, where Amtrak may have no clue how many times it was used or what the mileage was, they know absolutely that there were ten separate trips, on ten different days (or if it is valid either direction and physically possible to use both in the same day, then at least ten trips on 5 separate days, which is still no more than two segments per day) used with a ten-ride ticket. That doesn't make any more sense than only allowing the dollar points if I bought ten separate tickets and put it on one single Visa purchase.
As an aside, when you travel on a Florida Resident railpass, even though that is a "Flash Pass" which is unreserved and unticketed seating, Amtrak still actually knows your trip dates, train numbers, and segment mileages, because you have to fill out (and give to the Conductor) a passenger data form that has that information, along with your pass number, but you don't get any credit for those miles, either, on AGR. All you get, I think, is the value of the Pass, once, and nothing else regardless of how much or how little you use the Pass.