What's Special About A Linen Waistcoat?

Why do posh people like to wear linen waistcoats? Why is linen the fabric choice? There’s 10 reasons:

Linen is a natural fibre made from flax. It has a long history as one of world’s oldest natural fabrics.
High absorbent and a good conductor of heat means it’s cool to touch. Because it feels cool to wear [...]