Hi, Michael,
like I said before (e.,g. here: Will new patron be able to see previous month’s post? ) I personally don’t see Patreon as a “store” of any kind - but it is absolutely possible to use Patreon in that way, if you just accept the additional work you have to go through (like “paying upfront” and removing/shifting older content constantly).
I guess if someone wrote a tool that handled “Patreon as a store” (with the mentioned functionality), that might be a seller.
But, again, I see Patreon as a tip jar in the best case - and still consider those goof payments an annoyance. In fact, I find those bogus payments way worse than giving my content away for free, which is exactly the reason why I have switched most of my content to “free” 
Marc