Traffic. At my time if you wanted to fly VFR above 5000’ you had to give full position reports and next estimate to Flight Service. That was why we were the only country in the world that had a non ICAO mandatory radio requirement for VFR above 5000’
Are you telling me I could have flown around VFR at the same cruising levels as IFR airline aircraft?
And Bloggs wants to go back to those days?