Server push was never massively deployed because they may be harmful : the server pushes assets that may be needed by the client, but also may be already cached

Server push was never massively deployed because they may be harmful : the server pushes assets that may be needed by the client, but also may be already cached by the client. In the later case, this is a harmful burden, especially on mobile etc. The server is never able to truly know if the asset is actually required by the client Early hint is better, probably: the server quickly tells the client it will need those assets. The client can then decide if they must be fetched, or if they are already available.