I think it’s mostly true that things are stagnating compared to the century, or quarter-century before 1970. Some of that is simply because we’ve snagged the low-hanging fruit: You can only invent radio once. But I think there’s more to it than that.
In the United States, which drove most of the “golden quarter’s” progress, 1970 marks what scholars of administrative law (like me) call the “regulatory explosion.” Although government expanded a lot during the New Deal under FDR, it wasn’t until 1970, under Richard Nixon, that we saw an explosion of new-type regulations that directly burdened people and progress: The Clean Air Act, the Clean Water Act, National Environmental Policy Act, the founding of Occupation Safety and Health Administration, the creation of the Environmental Protection Agency, etc. — all things that would have made the most hard-boiled New Dealer blanch.
Within a decade or so, Washington was transformed from a sleepy backwater (mocked by John F. Kennedy for its “Southern efficiency and Northern charm”) to a city full of fancy restaurants and expensive houses, a trend that has only continued in the decades since. The explosion of regulations led to an explosion of people to lobby the regulators, and lobbyists need nice restaurants and fancy houses.
Maybe it’s just a coincidence that progress suddenly slowed down, but I don’t think so.
https://www.usatoday.com/story/opinion/2016/05/12/technological-progress-stagnation-regulatory-explosion-1970s-column/84225066/