A few weeks ago I splurged and purchased this Hayley Menzies dress https://hayleymenzies.com/products/beija-flor-cotton-volume-shirt-dress
I love the pattern and how easy it is to wear either casually or a bit more dressy. I purchased it knowing it was 100% cotton, and not silk or anything. But I've just gone to look at the care label and it says do not wash. Dry clean only. For an unlined cotton dress that set me back nearly £400 
I've noticed a lot lately that expensive 'designer' clothing isn't any better quality in terms of fabric. A lot I've seen is polyester, recycled something or other, or other man made fabrics. The cut of the clothing is usually nicer, but I'm a bit miffed at the fabric being used.
Can anyone tell me why this is please?