Lead stages application in sap marketing cloud

Dear sap community,

can anyone tell me the benefit and general sense behind the application "lead stages" in sap marketing cloud. I tried to find some information about that app within the administrator guide but was not successfull.

Why should I connect a lead stage to a particular segmentation building block?

And does anyone know a usefull busines scenario for this if a company allready replicates lead stages from sales cloud into marketing cloud?

Thanks for your advise,

Lukas