HTTPS certificates are a pain to keep up-to-date. Let's Encrypt makes it easier, but there's still a bunch of manual steps.
Digital Ocean could easily solve that inconvenience for its customers by providing support for Let's Encrypt.
A ton of hosts (ie. your competitors) already support it; see:
Digital Ocean should be on that list: it will make you more competitive, and it will make life better for your customers (or at least those using HTTPS).