If the odds generator was only seeded by the server, but run on the client, you could test the next run locally before deciding to place a bet. How would that make sense?
To clarify the claim a client makes on this site is that you have been around to make enough tokens to enter your info for the $500 monthly sweepstakes. Your slot results don't actually net you direct money or even improve your chances beyond being able to enter after a relatively low bar. Any server side validation would be to check you are a person who has been seeing ads and giving a real sellable email away instead of a bot trying to game the sweepstakes and, more importantly, lowering the resale value of the email list. Doing live server side hosting of every game spin would probably cost them more than they make, I'd be surprised if they even did the full level of server side validations available.
