When I hear "X would reduce GDP" as an argument against X, I'm increasingly skeptical. GDP per cap in the west doesn't matter, because we spend most of our money on things like houses/rent whose prices track GDP perfectly. Our world is just kind of broken on this issue.
Others are healthcare (US especially) and education. +-10% of GDP per cap - about 5 years' growth - is basically irrelevant in practice but in discussions people think of it as being a big deal.