There's something that happens when we are told about something so perfect, so in alignment with everything that we could possibly desire that we don't believe it. It must be 'too good to be true'.
Wool is the apex of fibres. It grows naturally with minimal inputs in nature. It keeps sheep warm through winter, then they need to be shorn anyway in Spring. It is soft, breathable, naturally adjusts for temperature and moisture and draws away smells and sweat then releases them, so needs far less washing. There are no known allergies to wool. At the end of its' useful life it decomposes quickly and beneficially in soil. It keeps its' shape over the years. Because it has a high water and nitrogen content it is flame retardant, and it also shields the skin from the sun with UV protection.
Given these facts, why did we become so obsessed with synthetic fibres? Reasons given include that they stretch, can be made waterproof and are stain resistant. That they don't wrinkle easily. But really the fundamental reason is that they are cheap.
They don't need to be grown, or collected, or washed, there are no seasonal cycles to making synthetic fibres. They can be made in a factory, and that factory can be located somewhere where there is no environmental accountability or workers rights so are synonymous with low wages, toxic waste outputs and harmful working conditions.
Synthetic fibres are made from non-renewing, non-degrading petrochemicals which are extracted from the earth in extremely damaging ways, from parts of the planet that are hard to reach, so often are homes to some of the most rare plant and animal life. They are plastics, same as yoghurt pots and water bottles. Extracting fossil fuels from the earth causes more greenhouse gases to be released into an already heavily laden atmosphere, and then processing them releases even more. And then, if they are not recycled (which requires more energy using mainly fossil fuels to do) they take many years to decompose and do so in a toxic rather than a beneficial way.
The dyes used to dye synthetic fibres are also toxic to humans, causing a range of nasty conditions to workers including cancer and lung diseases. And the fibre then continues to release microfibres into water when it is washed, which bind with harmful chemicals in wastewater, slip through treatment plants, end up in our oceans and enter our food chain.
These facts are extremely comfortable and highly inconvenient because 60% of clothing on the market today is made from polyster, and almost all cheap clothing is made from synthetic fibres. And when we've been told for many years that the most important thing is cost in money rather than cost in time or cost in environmental terms or cost in human endeavour it is difficult to see the wood for the trees, or, more pertinently, the wool for the sheep! Natural fibres is a great start to a sustainable wardrobe. Who knows where it may lead....!