Within the website https://www.tachytelic.net/2017/11/office-365-hide-a-user-from-gal-ad-sync/?doing_wp_cron=1520037861.8028988838195800781250
you are told that "It is possible to extend the active directory schema to contain the required Exchange attributes without purchasing or installing Microsoft Exchange server."
According to the article you can then use the ADSIedit.msc command to change the attributes for certain users (such as whether or not that user will appear within the Outlook Global Address List (GAL).
These attributes weren't visible before the Active Directory schema was extended but then become available after the AD schema is extended by running the following command from the Exchange server installation media: “setup.exe /prepareschema /iacceptexchangeserverlicenseterms”
I'm just wondering if there will be any issues with extending the Server 2016 Active Directory schema simply to gain these extended Exchange attributes when no on- premesis Exchange servers will ever be added to the environment (which is running Office 365 and is using Azure AD sync).