1) The hairs on the leaves and stems protect from drying out, reflecting light, reduce radiation, reduce evaporation, creating a semi-closed layer of air.
2) Hard hairs and burning hairs can protect against eating (nettles).
3) Feathered fruits and seeds are easily attached to animal hair or carried away by the wind (dandelion, poplar, etc.)
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.