closing an eye you lose field of view and all depth perception
do you close one eye drinking coffee? typing on a computer? opening a door? driving a car?
if you close an eye shooting your bow, there is a problem with eye dominance that you're ignoring or maybe a habit you've formed, and you can shoot all your life that way if you want to, but know what you're losing by doing it. finding what the cause of it is and fixing it opens a lot of doors (field of vision and depth perception being two very impoirtant thing bincoular vision provides vs monocular)