Meaning they're less defined by delivering a message, and more defined by the "value add" services they offer (like Payments, Notifications from third party services, customer support for third party services, etc).
RCS is more powerful than MMS, but less powerful than the internet-based messaging platforms it is competing against. It is also confined by geography, is confined to cellular devices, and disposes of anonymity/privacy.
Why would I want this? It takes me from the current requirement of "only needs an internet connection" to "need a cellular plan and device." It takes me from any moniker I want to [my phone number]. It takes me from "anyone in the world" to "US only." And on and on.
I don't get it. Why should I or anyone else care about RCS? Why do people? It seems like it solves yesterday's problems next week.