Just went through a similar discussion on another forum. The primary purpose of a 'stereo'
system is usually to create horizontal positioning and separation or to 'place' sources using aural cues based on the relative
level, response and timing between the left and right signals at a listener. You are trying to create with the sound
system the interaural differences between what is heard by the left and right ears that the brain uses in helping to establish the physical location of a source.
To get the same differences for all listeners requires that every seat in the
house get the exact same signal from each
array; the same
level, response, arrival time and so on, or at least the same difference between the left and right signals relative to the signals themselves. Even when you try to account for the physical relationship of the listeners to the arrays, the patterns of the arrays,
etc. it gets very difficult in most venues to provide the same experience for every seat. And when you don't consider these issues at all and simply put speakers located left and right then you usually get a
system to can vary widely in what is experienced throughout the audience area.
Adding to this, the room will also affect what listeners hear. In most rooms not everything a listener hears comes directly from the speakers, there is usually also some sound coming indirectly off the walls, ceiling,
etc. Again, how do you make the this component of what is heard the same for every listener?
The
point of all this is that simply putting speakers left and right does not make a 'stereo'
system for a
venue. there is potentially a lot more that goes into trying to support stereo for a larger audience. The issue often becomes one of balancing the potential benefits and disadvantages of the resulting
system. It is a generalization, but where intelligibility is critical and without proper design, simply sticking
speaker left and right may not have the advantages, and have some disadvantages, that have not been considered.
On a detail, you may also want to reconsider the title 'sound engineer'. Not only does that tend to imply a sense of professionalism and experience that may not apply but the Arizona Revised Statutes also state that ""Engineer" means a person who, by reason of special knowledge of the mathematical and physical sciences and the principles and methods of engineering analysis and design acquired by professional education and
practical experience, is qualified to practice engineering as attested by registration as a professional engineer." and that "A person or firm desiring to practice any board regulated profession or occupation shall first secure a certificate or registration and shall comply with all the conditions prescribed in this chapter." Looks like the state may restrict the use of the term "Engineer" to licensed professionals.