I will add that I think the argument being made is: it is received wisdom that if you don't ease the seam, you can't match up a pattern, and they are refuting t

I will add that I think the argument being made is: it is received wisdom that if you don't ease the seam, you can't match up a pattern, and they are refuting that. If I understand this correctly I think this article is right, there are geometric ways around that ... but I think the original wisdom applies to a context of fashion surrounding the sleeve cap. The way that the sleeve is attached is itself subject to fashion, such that easing is partly to achieve an effect, and not just to match things up.