I remember when I was a kid that you'd rock up to someone's house and they'd often have a huge collection of VHS tapes and CDs. Trawling through these was fun. You could learn a lot about a person by looking at their home cinema.
Physical collections are now dead. Netflix killed DVDs. iTunes killed CDs. Game collections are still clinging on but largely gamers will buy digital now as well.
This is sad.
I think entertainment collections leads to conversation which leads to discovery.
It promotes discussion amongst friends and family.
You also tangibly know what interests you have.
When a random person (let's say a barber) asks you:
What music are you into?
you have more knowledge on the topic.
I think I can make an app for keeping track of collections.