Community Points allow members of Reddit communities to own a piece of their community, earn rewards for quality contributions, and unlock special features.
Read all about it at the above link. There's way too much to process here. This is going to be wild.
Well, technically they can't. Practically, they can at any point just decide to not integrate that Blockchain they're building into reddit anymore, achieving more or less the same effect. Unless there's actually significant non-reddit applications working with it by that point.
Edit: oh well, just saw that apparently, access to your points is dependent on your "Vault", which exists in your Reddit app and Reddit can take away from you 🙃