Only 6 guys have ever done it. Being the worst of those still lands you easily among the all time greats.
Rory is tied for 15th in all time major wins and 18th in career PGA wins with plenty of runway left. These rankings includes a few Scots who racked up Open wins before WWI.
I don't think anyone puts him on the same level as Jack and Tiger but he's well ahead of Spieth, JT, Morikawa, Xander.