I’ve more than once seen the “overkill” system. It is often inflicted on small traditional churches who hire a big tech company to fix the sound system. They install something so complex that users barely know how to operate it. And when that “one guy” who knows how to run it takes a new job in another state… you’re in trouble. Why do they install these? I can’t speak as to motive but I think it’s because the designers tend to be sound techs. It’s easy for them to forget how overwhelmed you were the first time you sat in front of a mixing console. Sometimes it’s because the newest whiz-bang tech is what they think you want. It’s important to communicate what you need and if the company isn’t listening, move on. Sometimes it’s because there’s more overhead in selling you a bigger fancier system than a simple solution to your problem. Money makes the world go round.
A well engineered system keeps you in mind. Chances are, your volunteers are not full time sound technicians. They are just trying to serve the Lord and help out the church. A well engineered system is simple to use, simple to learn and as feedback proof as it can be, given the laws of Physics.