One of the most frequent arguments about the lack of modern geniuses hinges around the assertion that it was easier for geniuses of the past to make a mark and influence history, because there were so many 'low hanging fruit' - major discoveries just hovering there waiting to be plucked.
But nowadays, so the story goes, the early, easy, major discoveries have already been made; what now remains to be discovered is both harder and more minor - so that a modern person of equal genius to a famous figure of the past appears to make a lesser contribution.
Such an argument seems to assume what is false - that the quantity of human geniuses is constant in all times and places and among all people.
Nonetheless, let us assume it is correct: what then?
The importance of genius in human history - and specifically in modern society - is that the major discoveries (the breakthoughs) are so great and so fundamental that they enable a new wave of 'growth' to be built upon them.
But if we have actually (as the above argument asserts) run out of major discoveries to make; then the growth which depends on major discoveries will come to an end.
And since modernity depends on growth - specifically growth in capability and efficiency of productivity - then modernity will halt, then reverse.
So, the end of genius means the end of modernity; whether the cause is that we have run out of geniuses, or because we have run out of major things for geniuses to discover.
Either way, the consequences are the same.