I have had many Hotel managers and GMs tell me that staying guests are not supposed to get the points when dining in. They were surprised waiters were taking payment at the restaurants themselves because as one said, "That's not the way it is supposed to work." The goal is to get more business from people not staying at the hotel to drum up F&B revenue.
it is obviously more time consuming for waiters when paying guests pay at restaurant and get points, than a guest simply signing charges to room.
many hotel execs encourage guests to pay at restaurant because they know it'll net them more points. Hyatt people lke to make guests happen and help them find workarounds