Except that fit is often dependent on style. I have clothes in the same category but different styles from the same retailer where I need different sizes; heck,

Except that fit is often dependent on style. I have clothes in the same category but different styles from the same retailer where I need different sizes; heck, occasionally I've ended up having to compare different copies of the same garment in the same size, because copy variation made a worthwhile difference to fit. OK, maybe I'm a picky guy with my wardrobe ;-) Shoes, speaking personally, would be a total non-starter online. I seem to have narrower heels than many; I'll routinely find myself searching styles to find the ones that fit me properly there rather than slipping, even if they're right elsewhere. I'm sure some others will be a little wide acrosss the toes and need just the right level of bulging across the front, or a different arch height that makes positioning of the insole's mound under the bridge or the tongue important for their comfort. tl;dr: I can't always just buy a certain size and know that will be right. If your business model is dependent on that being possible, it won't work for me and I doubt I'm unique.