The idea that there could be a silver bullet comes from not understanding what software development is.
Model 1: Software development is like laying brick. Some cool machine will make it faster and easier to lay brick giving us a 10x increase in bricklaying productivity.
Model 2: Software development is like writing an encyclopedia. You have to gather knowledge, and then represent that knowledge in a way that's precise enough that a lump of fused beach sand can act on that knowledge.
Every improvement in software development "productivity" merely leads to a demand for more -- and more sophisticated -- knowledge capture.
We have had perhaps a 100x improvement in productivity since I started in the industry 30 years ago. But the demands grow exactly as quickly as our capability, so it never feels like we're getting anywhere.
Also. Few people code for 30 years. People that move into management don't see the productivity gains -- all they see is that their ability to manage a project remains really weak.
Sidebar.
The biggest issue is that the "silver bullet" crowd wants a definite schedule -- that's all they want -- a price and date that we programmers can actually meet. (There's that Model 1 assumption, programming is like laying brick.)
Eventually, some managers realize the software development is knowledge capture and they finally get "Agile". Others never get it and have a version of Agile that amounts to iterative waterfalls with extra paperwork and long meetings.