According to Osho, perfect vairagya—total desirelessness—is sufficient; then no practice or scripture is needed. But because such non-attachment is rare, yogic discipline serves as training: it refines the gross body–mind, tunes one’s inner ‘radio’ to receive the subtle, prepares the leap into desirelessness, and guards against chaotic, accidental awakenings. Discipline makes you a fit, receptive instrument so the divine can manifest through you and suffering can end.
If you’re already totally free of wanting, nothing more is needed; since most aren’t, disciplined practice tunes you to receive truth safely and clearly.