A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Your memory is perfectly correct, and you definitely CAN still copy from worksheets or charts and paste special/link to PowerPoint to create live links.
At least you can do this on the desktop version. Are you by any chance using the online/web version, though?
Also, it's possible that MS has resolved a long-standing bug that allowed you to paste/link from a file that hasn't been saved. I'll have to test this later, but check to see if the situation's different when you first save the Excel file, THEN (and only then) do the copy/paste.