I don't think it became a predominantly male occupation until it started to become industrialized. That probably also depends on location. I could be wrong though, haven't looked into it that much.

I also wouldn't go as far to say it was "traditionally" a male occupation... I'd say it became a male dominated occupation in "modern" history. It traditionally was a female occupation. From my understanding.

Good point nonetheless.

I think you underestimate the ability of local (individual) spinners and weavers of the time. A group of a dozen women could spin, dye and weave a surprising number of textiles in a surprisingly short period of time.

Source: see my wife's spinners guild, those old ladies can throw down some weaves. The technology is largely unchanged.

You can get dark and light patterns by using different colors of wool. They don't necessarily have to be dyed. They could have used wool from different colored sheep. I think the "true" tartans had reds, greens and blues in them, definitely dyed.