When you buy a timeshare, you get access to one of the exchange companies. BG uses RCI and BG sets up the RCI account for you. RCI is a separate company that offers several things - exchanging, renting, etc.
The 3000 point thing you mentioned is one of the options available via Travelers Plus called 'hot weeks'. It is very short term notice renting but it uses your BG points as opposed to paying. The inventory that is available for this is RCI inventory.
RCI offers various ways of renting. It has "extra" vacations, "last call" vacations, and others. Different pricing applies. Sometimes RCI will offer specials, much like a retail store has a sale.
So, owning a timeshare gets you access to the exchange company (RCI) which, in turn, gives you more options.