... How?
What I'm getting from what you and others are saying is that the silver standard just shifts everything to the right one category (if you would've found 150gp, you instead find 150sp; that's still 10 longswords at 15sp a pop). And a nation's GDP would be, instead of 1 million GP, 1 million SP.
Is this really just a labeling issue?
Sorry, I may have somewhat misunderstood your initial question.
As I see it, the term "Silver Standard" doesn't exactly mean a holistic shift down one coin type. The longsword is a good example. If a longsword cost 15gp before, it would cost 150sp after a shift to the silver standard. But, as you said, that loot that was once 150gp would instead be 150sp. Thus, you could only afford one longsword.
This is because a longsword is an expensive piece of equipment. Only soldiers and the reasonably wealthy can afford them. Full Plate is exceptionally expensive. Historically, a Knight was granted sizable land because he needed the income off of that land to maintain his armor and stable.
It's magical items that would see a dramatic price drop. A +1 flame tongue sword might only cost a few thousand silver, if you can find someone willing to sell.
That said, part of it is about making silver the metal you spend your time dealing with. In reality, a gold piece would be worth about $1000. So we'd measure the price of houses and cars in gold pieces, but for the vast majority of our expenses we'd use silver and copper. The silver standard it meant to reflect that.
I want the silver standard because I want gold to feel rare and valuable equipment to be a sizable cost.