Perhaps it is not buyers, but rather sellers. Bottom callers who think that is rich premium in the context of a 20ish VIX. In that case the houses would be the put owners.
When I did that and I had a customer dump a load of puts on me I would either
a) buy the stock, and convert the position to a call. b) create a calendar spread c) use it to hedge my existing inventory or d) if I didn't have much inventory I would get some, so my book wouldn't be imbalanced.