There is limited display space and not everyone wants a big collection, so the market was bound to be forever changed as more and more collectibles were introduced and possessing more detailed ones (e.g. not common things like flowers) became less of a luxury/sign of status.
I wasn't around when collectible stock was limited, so how did that work? Could someone theoretically do all of the events and obtain maximum currency, but because of bad luck, not be able to purchase something? It sounds like a nightmare to put forth all that effort, only to be able to throw it into raffles
(assuming they had those back then as well)