We use custom multi-instance datasources/properties for static information as well. Wouldn't want to put notes there, at least if conforming to our current environment standards.
The properties have no immediately viewable accountability or timestamp either. If you put in a custom property, the only way I know it's you is by reading the Audit logs (that only go out for one year). When was the note created (assuming user didn't timestamp it)? Who created the note (assuming the user didn't sign it)? When was the note last edited? I now have a note, but have to drill in the Audit logs first to see if it's even valuable and/or valid, assuming it was put in less than a year ago.
Ultimately, just looking for that Notes tab. If nothing else, simply for the convenience. Also, the aggregate time that would be saved over a long period while viewing/triaging thousands of devices. Looking to make engineers' and techs' lives easier while reducing clicks-to-resolution across the board.