I could go into mind-numbing level of detail about how browse structures work and what it takes to create new categories and re-assign listings created before the change, but you will all fall asleep.

Based on my experience, the short story here is that they very likely didn’t add activewear to the original women’s browse structure, realized that they should when they (later) added men’s, and are too lazy to do the tedious browse structure change and subsequent rule creation to reassign the huge amount of listings that are currently scattered all over the place in different categories. Creating a new category is one thing, but creating inclusion and exclusion rules to re-assign all the existing sports bras, leggings, etc into a new category is a huge pain. It’s easy enough to say all Chanel=luxury and plop that into a marketplace, but untangling the web of activewear being categorized all over the damn place would take a lot of work.

Not saying they shouldn’t do it, but I don’t work for them and I don’t have access to the data required to make a business case for dev resources to do their job for them. It seems like they mostly let the the site just run itself at this point.