Hey @SongMom8,
While it may not make sense at face-value, the feature works this way to streamline the user experience and minimize potential connectivity problems that may arise in the future
I belive that I actually reached out to our team for this exact concern when the feature first came out. If I recall correctly, the warning has to do with changes in the infrastructure of your network - meaning that if nodes become disconnected for an extended time (indicating a potential network change) these settings may not take effect due to all of these settings not being the same anymore. All Deco nodes have to talk to each other for this feature to work properly, and a disconnected node wouldn't allow the Deco to complete the checklist for devices with a connection preference.
Once the preference is set, the device can only communicate via that node. This means that if that node were to disappear, there would be no way to 're-do' the settings for the devices associated with that specific node.