E2EE is mostly useful for consumer applications, where you trust the endpoint (yourself), but not the intermediary servers (some megacorp that doesn't care about you).
The situation is entirely different when you are managing very large organizations.
In those situation, you don't necessarily need the need the data to be invisible to the intermediary servers, because you might either just be able to control them yourself, secure them with NDAs, etc. And if the server is controlled by you, then you might not even want the data to be invisible to yourself. But, your primary risks may be the compromise of endpoint devices, mistakes or leaks by your users, or a lack of controls over data exchange. Also, many organizations may need to provide records of their internal communications in order to comply with legal requirements.
You might be surprised to know that enterprise offerings of many apps that otherwise support E2EE, often have a way for administrators to intentionally turn those features off.
The situation is entirely different when you are managing very large organizations.
In those situation, you don't necessarily need the need the data to be invisible to the intermediary servers, because you might either just be able to control them yourself, secure them with NDAs, etc. And if the server is controlled by you, then you might not even want the data to be invisible to yourself. But, your primary risks may be the compromise of endpoint devices, mistakes or leaks by your users, or a lack of controls over data exchange. Also, many organizations may need to provide records of their internal communications in order to comply with legal requirements.
You might be surprised to know that enterprise offerings of many apps that otherwise support E2EE, often have a way for administrators to intentionally turn those features off.