DO is great for a lot of things, but it's not AWS. You can't allocate extra disk to a droplet, for example. AWS is a _much_ more complete offering than DO.
Agreed... AWS and Azure both offer a lot of services beyond just VPS hosting. Hosted database services, and extended blob/s3 storage are pretty valuable in and of themselves.
DO/Linode don't offer the equivalent, which means maintaining your own.. which is fine, but if you're relatively small, or a single person... time you dedicate to operations tasks is time you aren't developing features and/or fixing bugs. One's business is paramount... technology is just a tool to serve that.