Just to illustrate the point, dokku's docs[0] for logging say "Warning: The default docker-local scheduler will "store" these until the next deploy or until the old containers are garbage collected - whichever runs first. If you require the logs beyond this point in time, please ship the logs to a centralized log server."
Alright, well, that's gonna be a whole lot more work than two click in Heroku to send all my logs to any logging provider of my choice.