What I notice about systems like @Pixels is that the real difference is not in features or rewards. It's how people actually behave inside the system over a period.
When you have a number of users the design doesn't matter as much as how users interact with each other. It's the patterns that emerge from repeated interactions, consistency and how users naturally choose to engage that make a system feel stable.
Most platforms look similar at first. Its user behavior that determines whether they will be active, for a short time or a long time.
The users of a system are always changing it, not the people who write the code. The way users interact with a system shapes its structure over time.
Users decide how to use a system. That decides its long-term structure.
In a way users are always rewriting the system as they use it.