[ants_everywhere]

I agree. But to answer your question

> Why do we need platforms?

I'm currently of the opinion that hierarchies are partially an informational thing. Nodes that summarize or aggregate information from other nodes are higher in some abstract hierarchy (e.g. perhaps they have higher in-degree). Those abstractions tend to become more concrete and those nodes become points of centralization or what you might call platforms.

The platforms don't have to look like they do now (in fact I hope they don't), but I am currently skeptical of any perfectly flat communication system just on informational grounds.