The idea of on board speakers for me is to serve as a monitor ... no matter what position I need to be in to serve the room's needs. Sometimes the PA is not in optimal listening range for me, so the KB is my monitor. Since using the Bose ( 2 yrs or so, now )it's less of an issue, but there are still plenty of times that I only use the on board speakers. Nursing homes, cocktail hours, (some small)house parties ...etc
Speakers are a must in my rig. That's why I can't even compare models that do not offer them. They loose at the gate.
Everyone, and everything I listen to is my teacher. Every instrument, every voice, every sound in nature ... they are all my private tutor ... 24/7 for free.