I didn't know that BPs could be used to enter RCCs. Does this work when you are arriving at an airport and want to use the lounge as an arrival lounge (and you have no additional connections)?

I can understand how whipping out a BP would be faster than whipping out a membership card and ID. But what I don't understand is why people don't have room in their wallets because it's full of travel membership cards. Why are people carrying multiple airline and hotel membership cards in their wallets? Do you actually use all/any of them on your trips? I only use one travel membership card consistently and it's my UC membership card.