All depends on your target market. While social platforms come and go, we all have email. While younger people may not use it as often, they still have an address. If you give them something worth opening, they’ll check their email.
With social, you’ve got to pay to play, and be really good with customer targeting and copywriting. The competition is higher than ever and you play in someone else’s sandbox.
With email, you own your list and you control the delivery system. The short answer is you need both email and social.