Welcome to the forum @agentredgirl, thanks for joining! We did consider that storefront option but as there are so many companies doing that really well today, we wanted to create something a little different that ties into Patreon membership and helps creators keep patrons around for longer.
For the 3 months, we were imagining it being a surprise and delight moment for your loyal patrons. It can be viewed as a bonus perk for patrons as a thank you forstaying around for so long. They are still getting other items in that time frame, like being part of your patron community and access to patron-only content, and then after 3 months, a sticker or mug automatically arrives in their mail box!