Over-use of the hyphenated-adjective rule?

Sunday's New York Times Magazine included the following sentence:
"[Bill] Hybels, founder of the Willow Creek Community Church near Chicago, is very possibly the single-most-influential pastor in America . . ."

Are those hyphens necessary or correct per the hyphenated-adjective rule?
They are probably not necessary, since there would be no confusion if they were left out.
But do those three words truly comprise a single adjective? Rather, they are three adjectives modifying one another on their way to the noun.
We saw an example of this in a News Sentinel story about the faithful renovation of a 19th-century home: "John Roske lays brick using a special but expensive mortar most like the mortar found in the 1840s." No hyphens needed.
In the paragraph above, do we really need that hyphen between 19th and century?
In this case we would note the exception to the hyphenated-adjective rule, in which the hyphen is superfluous if the two or more words used before the noun as a single adjective are commonly used together, as in "major league baseball."