Why don't you keep cordova plugins under source control?

I have been working with hybrid mobile apps and consistently see the cordova-plugins directory is purposely ignored from source control. Why is this? All of these projects use Bower which is quite good at managing library dependencies, but it doesn't handle the cordova plugin requirements. Is it up to the developer who clones the repository to simply KNOW which plugins they need for the project?

If you want the same development environment on all the developers machines from the first time installing, check the Cordova hooks (http://devgirl.org/2013/11/12/three-hooks-your-cordovaphonegap-project-needs/).

Only problem after that is once your development environment is setup and someone decides to add a plugin the other developer will not notice that untill a platform remove and platform add again.

So version control is still not doable for all environments. If anyone has any ideas on that?