The big problem is that they don't grab the issues by the root.
Want better sperm count and fertility? Easy, reduce pollutants in agriculture, ensure food security for everyone, ban pesticides + GMOs, reduce toxic chemicals in industry, reduce plastic use etc
Want more people to have children? Then don't make it hard for them to raise the child, make it easy for women to go back to work without having to neglect the child, establish paternal leave, build a society that is welcoming to children.
But what do they do instead?
Fertility treatments with frozen spern and eggs, surrogate pregnancy and all that weird stuff.
Then mass immigration, destroying entire cultural identities, forcing people from 3rd world countries on arduous journeys where most of them die miserable deaths. These people wouldn't come if we, the 1St world countries weren't responsible for most pollution, causing climate change, droughts, rise of sea levels. Additionally, the west fuels local and proxy wars,making many countries so unstable that war doesn't end for decades. Ofc people will want to leave such places, can we blame them?