Not for a lack of trying, which is exactly the point. The fighter who does the ducking is the one whose legacy suffers.
If you examine the "name fighters" on Dempsey's resume as he rose the ranks you see that all but Fulton were on losing streaks. After the John Lester Johnson fight, and the change in management, his opponents were very carefully picked… which is management's job. Still, it doesn't flatter him when this list of opponents is examined. It can be argued quite convincingly that best live body he fought before Tunney was Fulton.
Harry Wills. His 1914 victory over Sam Langford alone trumps any of Dempseys wins. Dempsey turned down a fight with Sam in 1917.
Greb. It's silly to dismiss him because he was beaten past-prime by Tunney after chasing Dempsey for eight years. Greb utterly thrashed Gibbons in a title eliminator. Dempsey fights Gibbons. Greb beats Miske. Dempsey fights Miske. Greb utterly thrashes Brennan...four times. Greb wants Dempsey. Dempsey fights Brennan. Greb utterly thrashes Battling Levinsky. Greb wants Dempsey. Dempsey fights Levinsky. But because Dempsey "beat the Tunney that beat Greb" it somehow doesn't matter that he ducked two, not one, but two men for his entire reign and they happen to be the men that it was PROVEN would have given him the toughest time. It's an embarrassment. That, above, is a total embarrassment. Imagine Muhammad Ali ducked his #1 contender for his entire reign and then repeatedly fought the wash-ups of his #2 contender??? The rope that Dempsey gets on this forum is absolutely incredible.
You could go further and say that the only one whose legacy suffered was the prospective winner. It's interesting for me. I have Wills and Dempsey both outside the top ten but inside the top fifteen. For me, if one or the other had sorted that out - say Dempsey SD15 Dempsey KO9 - would he become a legacy #3, all other things being equal? Also, I would suggest that boxing's failure to deliver that fight was equalled only very recently by the failure to materialise Pacquiao-Mayweather, and that before it, only Sullivan-Jackson comes close in gloved history.
Out of curiosity, were there ever discussions for a Greb-Wills fight? Seems weird at first glance that two guys with a storied history of fighting everyone (and winning most of the time) would be chasing after the same fighter for years without their own paths crossing, even taking the size disparity into account.
Tunney tried to get Wills to fight but Wills declined probably correct in siting that he had been ducked for the #1 prize for so long, why would he settle for #2 As for Greb, I don't recall reading such a thing. Kompton would know best.
I don't think either guy was on the others radar. Greb has nothing to gain by fighting a guy who is 8 or 9 inches taller and 50 pounds heavier and Wills has everything to lose by looking foolish against a middleweight. But that's the advantage of being a contender and not champion is that you can't argue who's ducking who. It's why the Pac-Mayweather debate was so polarizing.
I think Rickards plan was just to keep matching Wills against the top white contenders, until one of them inevitably beat him. Wills was no fool, and he saw through this.