"Men's sperm counts have gone down by half in the last 30 years in industrialized countries"

The bad is that this probably extends to other health problems too, besides sperm count.

Otherwise, as this fun comic/charge[1] shows, would not be that a big problem for everyone.

1- https://dilbert.com/strip/2014-04-05

:last addition: Sperm swimming speed is probably affected as well.