I think that itch.io would really benefit from the ability to sell merch much like how bandcamp does. There are a few reasons I think this.
* I think merch encourages niche users to become long-term investors in a website. This is purely a personal experience for me, as I have always been a music pirate, but bandcamp has managed to sell several thousands worth of music to me due to their thriving cassette culture.
* I find it odd that current users link to external sites like bigcartel when the revenue from the transaction would be better placed here.
* bandcamp has already drafted out logistical concerns that have been in practice for many years without issue.
* Their TOS state that they withhold responsibility from merch, and that could easily port over here
* Implementation would require a page that lists current merch orders and their status, a shipping label generator, and (most importantly) a way to limit stock (which I think may have been implemented as a one-off for a previous user) for a given release. Adding multiple states of a game to be sold (i.e. game option 1 has unlimited stock with digital download while option two has limited stock with additional merch) would also be beneficial.
I really think that Itch.io could be a popular distributor for indie gaming zines and floppy disks, and maybe actual physical game releases since buying hardware on steam only feels natural for steam-branded hardware. I don't think there is a major option for indie games releasing small-stock game hardware outside of piggybacking off of etsy clones, and this is a niche that itch could easily fill.