All the reasons for applying a screen protector do not apply to a MacBook Pro.
• MacBook Pro does not have a touchscreen. There is no need to protect it from rough touches, because you do not need to touch the screen at all.
• The other reason users put protectors on iPhones is to protect against dropping the screen on a rock and scratching it. The MacBook Pro does not open far enough to drop its screen on a rock.
Since the screen coating could be damaged by applying a screen protector, and Apple warns you NOT to use one, there is no justification for using screen protector.