One benefit for me was that a vps with 2vcors and 2-4gig of ram is about the same price as one of these app engine services. So I can run 3 or 4 dokku apps including Postgres, redis, memcache connected to them on my own vps and still have margin when inspiration strikes. I moved a production app from heroku to dokku and saved hundreds a month and still got tons and tons more compute.