What are the problems with email? For me, it seems that having internal mailing lists that anyone can subscribe to (sometimes needing approval, like ceo-staff@)

What are the problems with email? For me, it seems that having internal mailing lists that anyone can subscribe to (sometimes needing approval, like ceo-staff@) allows for structured topical threaded discussions that are archive able and searchable. Other than one-off q&as, I don't understand why email isn't still the best thing we have?