FWIW, I have found one of the best parts of using Digital Ocean is their fantastic documentation and tutorials. As a relative newbie, I was encouraged to deploy to a PaaS such as Heroku but grew frustrated at the black box aspect of what was going on underneath the hood. The tutorials on DO allowed me to learn and gain an understanding of how servers really work.

On your point about database services, I was able to set up Postgres on my droplet with relative ease and it has been serving me well ever since, again all thanks to clear and well made tutorials. I think if I could do it without any prior experience, most other people can too. So IMO, these providers aren't necessary at all.