something something ww2
The only explanation I have for this phenomenon is that this was in the news media a lot in the 90s, but so many other things were in the news more, but this thing seems to have entrained itself as the first thing that comes to mind when mentioning Switzerland.
With the 90s you mean the case of Christoph Meili? Maybe it's because it's a spectacular case and that makes it brought up more.
Meili was part of it, it basically goes from 1995 to 1998.
For what it's worth, I took them to mean "Did not suffer significant population losses, widespread physical devastation, and exorbitant military expenditures during WWII, and so found themselves in a much stronger economic position than all the other major European countries in the decades that followed". I don't understand why you seem to have a different interpretation, especially one that you yourself describe as "baffling" and "not relevant" to the question of national wealth.