There are very few places where business rules change so quickly that a rules engine is needed. Rules engines are essentially a poor practice used by businesses who don't clearly define what their goals are and stick to them. The alternative is to have a highly modularized system that is flexible enough for engineers to make changes to the code base in a timely manner, but that requires business to sit down and define the problem(s) they are trying to solve with their software. Getting that sort of time investment is difficult.