I read a great article about this the other day. I'll try find it again, but basically this guy, an outdoorsman, went through a transition back to natural fibres and recalled how his old school mentor used them. He goes through how he, like everyone else, moved to plastics with all the innovation, but journeyed back to natural.
The most poignant points for me were mentioning ions and HOW the fibres breath.
He said plastic fibres block certain ions, which sounds a bit fairy, wishy washy, but it may be based on science. Bodies of water being close do actually have a physical affect on us which is scientifically measurable. It is mentioned in an episode of 'down to earth' which focuses on water. It mentions positive and negative ions being affected in our bodies.
We are told that sports clothing is breathable and wicking, but those terms are not so simple. Not absorbing water isn't always good for example. I always find I feel sticky and clammy after wearing polyester sport tops. I wouldn't call them breathable really. Just quick drying.
They also absorb lots of bacteria and stink.
I'm definitely looking into bamboo now. I find wool socks make my toes sweat and the pure t shirts are a bit too hot and itchy, though pretty good still. A wool shirt would be good as a mid layer though. Maybe a wool jumper.
The main issue is the waterproof outer shell