Hi Elizabeth,
I don't think you should worry about keep your finds current for the benefit of others. Our intention with the feature was focused on giving you a way to manage all the items you are considering for the future and have purchased in the past. The fact that other people can discover items when you collect them is a nice byproduct, but not our focus.
Also, the feed of items is is in reverse chronological order (latest first) so items that are no longer available are less likely to be seen.
Also, we like that old (unavailable) items will still be in the system. In fact, it might be the only record after retailers have removed the item from their systems. And it might still be relevant to you (inspiration, in your wardrobe etc.).
Finally, at some point in the future we would like to hook up finds to a live product database, so we can give an indication on the card whether an item is still available.
Long story short: don't worry about keeping your collection "current" unless you want to do that for your own purposes.
Greg
