The article confuses "exponentially" and "quadratically":

scales roughly quadratically with the issue-width. That is, the dispatch logic of a 5-issue processor is twice as big as a 4-issue design, with 6-issue being 4 times as big, 7-issue 8 times and so on

Searching online, it seems that quadratically is correct; the explanation of "quadratically" is the mistake.