This is 100% correct. If you go look at the Chef cookbooks for any popular piece of software, say Apache or MySQL, the code is littered with conditional logic and attributes for different Linux distributions (not even considering entirely different operating systems). Every distro has different packages as dependencies, install locations, configuration file locations, service management, etc.

Docker (all container solutions really) aren't a panacea, but they solve a very real problem.

By portability I was referring to being able to move your application to different servers by running your provisioning system.