The difference is that the stuff you buy “on the spot” is tested by locals in that environment. In my experience, I got my favourite rain gear from a local store in a place where it rains a lot, and the best mountain gear in a town that’s actually in the mountains. Online shopping, even with lots of research, can only take you so far.

Also, these things make great souvenirs. Every time I wear my merino wind buff, I think of that little Irish town on the Atlantic coast where I bought it, and how wet and windy it was.