Do I Need to Use Sealant? If I'm using a pair of "fully sealed tubeless rims" do I need to use sealant?

I'm seeing some sites state that it is unnecessary.

This question is really spawned by the statement that sealant corrodes rims.
If the rim is tubeless (fully sealed) and the tire is fully tubeless then correct you do not need to use sealant.  

Tubeless ready tire then you do need to use sealant.
A benefit of the sealant is to also repair small holes.
Fully tubeless is a heavier tire.
Tubeless ready with sealant is more common set up.  

Some tubeless rim manufactures such as Stans recommend tape to protect from corrosion from the sealant.