Characters in Poul Anderson's Operation Luna speculate -
If Einstein and Planck had not cooperated in 1901, then they might have developed distinct, mutually incompatible, theories of relativity and quantum mechanics instead of the single theory of rheatics.
Next, if Moseley had not released goetic forces by applying rheatic equations and thus degaussing cold iron, then:
fossil fuels and electricity would have been major energy sources;
transport would have been by horseless carriages or dirigibles;
astronomers would have analysed spectra, not spectres;
paranature would have remained Asleep, concealed;
witches and warlocks would have been cranks, not respected professionals;
werebeast DNA would not be understood;
those who had maintained magical traditions (Africans, Australians, Native Americans) would not have had their head start in practical goetics.
Imagining inhabitants of other timelines speculating about our timeline is a way of commenting on our timeline. I have found some comparable examples of this in graphic fiction -
A DC Comics supervillain, traveling between alternative Earths, claims to have found one where no one has gained any super powers. A colleague comments that that sounds unlikely.
Superman flying between parallel Earths passes briefly through the sky of Earth Prime, where superheroes are fictions. A man looking up shouts, "Look, up in the sky, it's...it's nothing!"
Alan Moore's Watchmen universe had real superheroes so their comics were about pirates, then horror, and a comics shop was called "Treasure Island," not "Forbidden Planet."
A Watchmen universe newspaper headline asks "RR for President?" A character asks, "Who wants a cowboy actor in the White House?" We realize that they mean Robert Redford.
One of the "Watchmen" comments that the US would have gone mad as a nation if it had lost in Vietnam.