If you doubt this, consider the choice proposed by Professor Gordon. He asks you to choose between having all the technology developed since 2002 and no running water, or running water but no post-2002 technology. We'd all choose the latter. Which shows that just one of many late 19th century technologies is more important than all 21st century ones.
Not only has the boost to growth from innovation slowed, says Professor Gordon, but the US faces several "headwinds" constraining growth. The retirement of baby-boomers, the end of the growth in university education and in human capital and policies to combat climate change will, he says, also slow down growth. He thinks real GDP per person could grow by less than 1 per cent in coming years, rather than the 2 per cent we've seen in the last 100 years.