Is a Hybrid Exchange Server Required

Hi,

Simple question hopefully - what does a Hybrid Exchange Server do for us and should we just let it go. 

In our environment all (~120) mailboxes have long been migrated from on-prem to either remote user or remote room mailboxes. Currently the on-prem exchange server does do anything for us, I believe, other than that we use it as a GUI for distribution list membership management and a tool to create and migrate mailboxes to EOL (using enable-remotemailbox in EMS).

Where there are no on-prem mailboxes remaining, does an on-prem hybrid Exchange Server serve any purpose? should we simply turn off this server and perform the above mentioned tasks some other way? Does the Exchange server play any part in client (i.e. Outlook) connectivity?

Thanks