Deciding to join an ecosystem as a creator is about the short term benefit vs the long term downside.

Once creators join into an aggregator it's very hard for them to leave. But they can decide not to participate.

The short term benefit might be marginal user traffic or engagement to your content.

The long term downside might be tying yourself to an entity that will have increasing power or control over you.

Submitting yourself to a feudal lord that grows more powerful every day.

That feudal lord may change the rules later in the game in a way that significantly harms the creators; almost every aggregator in history has!

Only if the short-term benefit beats out the long-term downside will the marginal participant decide to participate.

But of course the short-term benefit is often concrete and clear and the long-term downside is often diffuse and abstract.

This gives an edge to the short-term benefit winning out.

However, when the marginal entity is deciding to participate, if they have two options, both with roughly equivalent short term benefit but one with significantly lower downside risk, they will have a distinct edge to the one with the lower downside risk.

This can often be a small but distinct asymmetry, an edge.

Ecosystems have significant network effects, which means a consistent edge (even a small one!) can rapidly accumulate an overwhelming advantage.

A small but consistent and distinct asymmetry with a network effect can become a hurricane.

This is why if there's an open system that is roughly equivalent in short-term benefit to the proto-aggregator, the open system will win.