There are many lifestyle / category based mobile buy/sell marketplaces:
For example:
https://poshmark.com/ - womens fashion
https://sobump.com/ - streetwear
https://depop.com/ - creatives marketplace
https://www.etsy.com/ - maker/vintage
... many more
To me, this is like user forums before reddit/subreddits came along.
My question is: Why isn't there an app that lets users create, curate, and shop all of these topics in one spot. Each one of the links listed above would be analogous to a subreddit on the platform.