There's a couple benefits to using this, including the option to integrate load balancing as well as the extensions (such as database servers) that are the cheapest you'll get anywhere unless you set them up yourself on EC2 or a VPS.
Have you seen AWS? Elastic Beanstalk and RDS are pretty affordable solutions that our startup is using to allow us to scale when we need to.
The best benefit of Fortheon is that all your servers traffic is run through your own system that you built, load balancers, etc. but it's super easy to configure.
This looks like a heroku competitor whereas dokku is a self-hosted option.
Exactly on point, Dokku is great when you want to manage everything yourself, but Fortheon takes care of all the hairy server interactions.