Dan Dennis said:
Y'know, Art Fleming was actually an actor (albeit in small bit parts) when he was offered the hosting job on Jeopardy! by Merv Griffin. So he figured he'd play the part of a game show host. Why not hire an actual actor to be a game show host? And I'm not talking about guys like Will Ferrell or John O'Hurley. Someone who has only done bit parts, like Art Fleming. Let's not hire someone with big name recognition (a la Matt Lauer) who will tend to overshadow the game. What Jeopardy! needs is someone who can keep the game rolling, be personable, let the contestants' personality shine, and simply host the game. After all, when Don Pardo announced the show he always introduced Art Fleming as "the star of Jeopardy!", while Johnny Gilbert introduces Alex Trebek as "the host of Jeopardy!". There's an important distinction there, I think.
To elaborate on your point, Mark Goodson used to give his hosts the choice of being introduced as the "star" or the "host." Bob Barker and Gene Rayburn, IIRC, opted for "star," but Larry Blyden insisted on "host." His point was simple and logical: there are genuine stars (he named Barbra Streisand as an example), but seemingly every two-bit local personality insists on being called "star," which they are definitely not. And while he'd done some Broadway and a couple of short-lived sitcoms ("Joe & Mabel" in 1956, "Harry's Girls" in 1963), he did not consider himself a star. And there was one who was so big all Johnny Olson or Bill Wendell had to do was say his name: think back to "To Tell The Truth" in the '70s and the opening, "Ladies and gentlemen, Garry Moore!"
Art Fleming had played on the Western "The Californians" for one season (1958-59) but IIRC was anchoring WNBC's 11 PM news when Merv first saw him; likewise, Pat Sajak was doing the weather on KNBC; his predecessor on "Wheel," Chuck Woolery, had been a frequent guest on Merv's show, trying to establish himself as a country singer, but proved to be a better talker than singer. I also believe Mike Reilly had been a contestant on "Jeopardy!" and impressed Merv with his personality (whatever happened to Reilly anyway?).
A few others Merv hired who didn't quite fit the mold:
Joe Garagiola ("Joe Garagiola's Memory Game")--he'd done "He Said! She Said!" and would replace Jack Kelly (another off-the-beaten-path choice by another producer) on "Sale Of The Century" (and would also host the 1986 version of "Strike It Rich"), but better remembered as a baseball player and announcer.
Bill Mazer ("Reach For The Stars")--another sportscaster.
Danny O'Neill ("One In A Million")--that was in 1967 and I still don't know who this guy is or was.
But after all, Bill Cullen, Bob Barker, and Gene Rayburn couldn't host every show. And whether or not you like Lin Bolen for tearing up NBC's daytime schedule she did give Trebek and Woolery their breaks.