Why can’t Merino wool be replicated? Could a cheaper, artificial alternative be created without sacrificing quality?

No natural fibres can be “replicated”.

The reason is that all natural fibres are fiendishly complex in structure. We’re probably closer to replicating a sheep from raw atoms than replicating wool.

This is what you’d have to recreate in your lab. Good luck with that.

It’s not much simpler to replicate a plant fibre like linen:

There are, however, innumerable artificial fibres, mostly derived from petrochemicals, which mimic the qualities of natural fibres. Most can only imitate the feel of the natural fibre. For example, acrylic fibre has the softness of wool – but not the warmth, rainproofing, elasticity, inflammability, or biodegradability; and acrylic has many disadvantages besides, such as being a significant source of microplastic pollution in fresh and saltwater.

I prefer nature.

Quora linky.