Digital Ocean started as a lower-priced clone of Linode (Vultr did the same later). They started with just a subset of the services (finally catching up now), but had good developer marketing and a lower starter rate.

It'll be interesting to see if they can continue to grow now that Linode have reduced prices to be lower than them. That's one big catch with coming in at a lower price, the incumbent probably has the scale to lower their prices below you, if they consider you a threat.