How does it benefit you not to have rules saying the benign dictator can't beat you for no reason?

When one can rely on the benignity, probity, and sound judgement of the dictator, such rules are unnecessary, although publishing general guidelines can be useful to let everyone know where they stand.

Also, we don't know who the dictator is, or how many of them there are.

The dictator is Eliezer, acting directly or through whoever he delegates any matters to.