Making it available to all ranks is nice in theory but then you make it more likely that the catalysts will be added to current gathering nodes rather than create new ones. I mean let's say they created new areas for catalysts. Where could you suitable place more grade 1, 2 or 3 areas? It's easy to find more locations for higher rank grades and at the end of the day you can take a gathering class to 28 to scan grade 4 in about two weeks.