MM Management Access - why so useful?

I have often read that MM‘s are leveraging good management access but I am somewhat confused by the actual nature of this "access". Maybe I am just completely ignorant or get something wrong here, but if the baseline is that management is not allowed to share any material non-public information (maybe my definition of this is wrong?), how can it be so useful?
 

If they don‘t share anything that is 1) material 2) non-public, what‘s the benefit? Or is the legal definition of either 1) or 2) just very lax?

Thanks!