Well the reasons for each point are a bit different so let's go through them one by one.
A declarative language cannot be general purpose by definition.
Succinctness. If you know exactly the domain you are talking about it means you can use many shortcuts and abbreviations that would be unclear otherwise. We all know this is true for natural languages, and it is also true for programming.
Close to English. In this case the reasons are more about aesthetics. English is not particularly good for general purpose computation as it struggles to express complex ideas with enough precision that it is crystal clear what is meant. A reader must apply some common sense to disambiguate. A general purpose language close to English would either be a Turing tarpit, or it would be a close-to-english language with some general purpose computation things bolted on.
