A long time ago, I made a post wondering why there was so little “middle-tier” alternate history. Why was there so little alternate history that wasn’t either blatant or technical. There was a discussion to this end on Sea Lion Press some time ago, and (at least partially) from seeing and participating in that, I had an “ah-hah!” moment that might help explain the reason why.
The reason is simple: What would be “middle-tier” alternate history isn’t sold as or even considered alternate history most of the time. Using a ridiculously expansive definition, anything that isn’t an explicit reenactment/retelling of a historical event can be considered “alternate history”. A fictional city? Alternate history. A fictional political leader? Alternate history. A never-was weapon or car being used because the author liked it? Alternate history.
Even in lesser cases, where there’s a clear timeline divergence, it could be considered alternate history, but isn’t. For instance, since the timeline diverged in the 1980s with the arrival of Scion, Worm could be considered alternate history.
The sad truth (for alternate history fans) is that there isn’t much gain in labeling something alternate history. It’s known, but it’s known as a genre where the divergence is clear and blatant. For a more mainstream audience, it’s been shown that it’s better off being labeled as just what its genre is-a thriller, a mystery, or whatever it might be.