Not me, but I think that the fundamental argument is quality / quantity.

The quantity side aligns with capitalism and growth for the sake of growth. More consumers. More labor. Supporting the top-heavy aging populace (admittedly a problem) by whatever means necessary. Quantity is an argument favoring people not yet born, or favoring a pyramid scheme by which there needs to be an ever-expanding base of young, productive people to support the old. Nonexistent people's "wants" should not be considered in any way. If they are not born, they can not suffer. We should not consider what hypothetical people might have wanted. The elderly need to be supported, but by some other means. We cannot continue growth forever simply to support all those who came before us.

The quality side is benefit for the existing populace. As a person who exists, it's basically the only thing I care about. I prefer my quality of life over sacrifice for the potential existence of not-yet-existent lives. I think any sane person would want there to be more quality of life for themselves and other people living. Quantity of life directly impedes this goal.

The previous poster may not have stated the case as such, but I believe that it is self-evident.