As Sylen says, the game's primarily designed around 1-8 player co-op. Further, Most people play with their friends in private servers (Dedicated or non) that are passworded so only they can enter. More still just play solo, Or pick up friends from the meeting room- but again, passworded and private.
Not many people host public dedicated servers that aren't PVP centric, because there's just no way to verify that anyone who joins doesn't come with ill intentions- And most people don't want to come back to a ransacked base, Or get screwed over by a random training zombies on them and other such stuff.
There are no Developer Owned dedicated servers like other games- Everything is player hosted.
Not many people host public dedicated servers that aren't PVP centric, because there's just no way to verify that anyone who joins doesn't come with ill intentions- And most people don't want to come back to a ransacked base, Or get screwed over by a random training zombies on them and other such stuff.
There are no Developer Owned dedicated servers like other games- Everything is player hosted.