What your casual elitism disregards is that people who actually do the work can have different ideas, especially related to the work they are doing. Put another way, since they have a different perspective than the higher-ups, they are sometimes able to find potential efficiencies and product improvements that wouldn't occur to others.

Additionally, front-line workers can see real problems with how customers experience the product that may not be reflected in the metrics used to evaluate the product, since metrics are inevitably gamed.

The ratio of good to bad ideas doesn't matter if you miss the one good idea you really needed. A company that invests in ways to effectively use the ideas of 'untrained people', as you so delicately put it, can derive a lot of value from those ideas.