There is no problem creating a system from past results PROVIDING the parameters and filters you set are based on fundamental principles and research.

For example: 95% of horses cannot carry 69kg and win over 3200m. That is not likely to change in the future unless horses are allowed steriods or the weight scale changes dramatically.

Betting on TAB numbers etc are not fundamental principles, but doing research on the way horses perform in general and the impact of extra distance and weight etc are.

Not all systems are **********. Not all people who provide a service to punters are ******** artists either.
The problem is sorting out the honest and legitimate ones from the thousands out there.