Lets say that Harry Wills was as good as you say he was. We have to consider him to be part of the era, whether he fought Dempsey or not. By your argument, the presence of Dempsey and Wills in the same era, makes it look very solid!
Tommy Loughran basically won his fights with the jab....he was a jabbing specialist as a matter of fact.
Anybody that boxed after the 70's is pretty much either overrated or at moderate level.I think everyone agrees to that because boxing skills started to decline soon after. I realize this now and come to that conclusion since only watching mostly black and white t.v eras ...mainly Jack Johnson and Gene Tunney.
If you think any era is better or poorer than the one before or after it a quick look on BoxRec will usually throw a spanner in the works. It's littered with old stars beating upcoming fighters who later went on to become top stars in their era.
I remember following boxing in the 90s and thinking it was a barren era for boxing, particularly when comparing it to the previous decade. The fighters felt a lot more low profile in the 90s and the general public didn't really care about anyone other than Mike Tyson. When Tyson came back and was pronounced the saviour of the sport, I knew things were messed up. Looking back now, though, the 1990s seems like a relative golden age compared with now. The talent pool seems thinner than ever, the lack of genuine world class and marquee fighters (especially ones in their physical primes) is so small it's pretty pathetic. This is a terrible era right now and I don't see it getting better, I'm afraid. But if anyone can shine a more positive light on things, I'd welcome it!
You ultimately have to decide which way you are going to jump on this. If Wills was such a colossus, then the era contained two great heavyweights. If he wasn't that special, then it is not as detrimental to Dempsey's legacy, that he failed to fight him. There is another problem. Although Dempsey is regarded as being a strong champion, and he missed a couple of key contenders, his opposition was still able to put up some effective resistance. No champion seems to be so strong, and no era so weak, that there isn't some sort of effective challenge mounted.
Plenty of eras had two great heavies. Almost all of them did. That doesn't make the era especially strong. I don't consider Dempsey's reign as being particularly strong. The fact his opposition was able to put up effective resistance may speak more to Dempsey's ability and focus in defraying this resistance than the quality of resistance itself.
It probably means that it is not a weak era. There is always effective resistance! However weak the era, however many contenders the champion swerves, however good the champion is. Many people say that their favorite fighter x, would have gone through everybody without breaking a sweat, if only he had fought in era y. The reality however, is that there is no era where that actually happened!
OK, so lets take our conclusion a step further. We never had that magic moment, where a prime Mike Tyson emerged, and knocked out all of Rocky Marciano's opponents in a few rounds each. Every time when it looked like that might be happening, order was restored when the champion went up against the top ten, on a regular basis. That is why I always place some weighting upon dominating an era!
I don't see how this negates the premise that certain eras were depleted unless you measure eras with a longer yardstick.
My point is that a depleted era, is still not easy to assert your authority over. Even for a great fighter. Everybody has two hands!