Bring back Label Engine Warning when adding a maplex layer into a standard label engine map

[LyonMNGIS]

Hello

Please bring back the alert that warns if a user is trying to add a layer that contains maplex properties into a map that uses the Standard Label Engine.  This feature is useful in ArcMAP so that users don't accidentally delete maplex properties when they add a maplex enabled layer.

*Note:  I realize this is not a huge issue in ArcGIS Pro as Pro defaults to the Maplex Label Engine...  Still it might not hurt to keep this warning.

Thanks