[Wayne A. Pflughaupt]

And indeed, why notch filters should be avoided is fully discussed in the second post of the article...

From what I’ve seen the two go hand in hand. All things being equal, the use of broad filters will generally require fewer filters to fully equalize a response curve. By comparison, notch filters can only move small “chunks” of graph “real estate,” as it were, so more of them will be required.

Regards,
Wayne