The meditation method we teach is of Buddhist origin, therefore many of its most experienced practitioners are Buddhist monks. Historically, monks and ascetics were the gatekeepers & preservers of meditation knowledge, and this is an ancient practice we hope to revive in the modern era. While lay meditation teachers certainly also have their role, the benefit of having a monk as a meditation instructor is that monks are professional meditators who live and breathe meditation.
Imagine the difference between having a personal trainer who knew how to give you instructions and do all the exercise motions but wasn't much more fit than you; versus having a personal trainer who could do the same, but also had your ideal body shape & fitness level. Having a monk as a meditation instructor is the mindfulness equivalent of having that ultra fit personal trainer.