I think you're kind of wrong here. DO's biggest thing for me is that it's incredibly easy to use while providing all the baseline features I actually need for casual hosting. I guess you could count this as 'marketing', but I think there's a strong technical element to knowing your market and how to make what they want to do as easy as possible. DNSimple occupies a very similar niche.
In fact, part of the appeal may be that they don't use openstack, because openstack implementations to date have all been quite limited and complicated so far.
For me, it's all the pricing-reputability ratio. They've always seemed like a stand-up company, while offering a comparable product to Linode and similar...at a fraction of the price.
I jumped over to them around the time NewsBlur wrote that post about scaling to meet the new demand when Google Reader shut down. I had never heard of DO before that, checked them out, and made a the switch after a bit of research.
I use DO as a private little always-on server, I don't actually host anything worthwhile with them.
I signed up mostly because of the $5/month price and the $10 credit. That's half of what I pay for my main hosting account (over at WebFaction) and year, is about what a nice meal out costs. It's nice, quick enough for all my needs and took minutes to set up.
In fact, part of the appeal may be that they don't use openstack, because openstack implementations to date have all been quite limited and complicated so far.