Multiple Source Path in One Maven Project

Question

Why is it that the build management tool Maven restricted only ONE path for source, ONE path for script, and ONE path for test source?

 <sourceDirectory>xxx</sourceDirectory>               
 <scriptSourceDirectory>yyy</scriptSourceDirectory> 
 <testSourceDirectory>zzz</testSourceDirectory>       

When using a plugin such as the mojo build-helper-maven-plugin, I add multiple source path to one Maven project. What's the risk for not organizing all the source code, script, and test source code?