While the concept of a "necessary backing" is a fallacy in my book
"Backing" is a kind of awkward hack that attempts to limit the production of currency.
It never really worked in the first place, and it's completely unnecessary now that we can just use math to limit the supply of the currency.
Well put.
The 'backing' concept still remains a rhetorical argument against things like Bitcoin by people that imagine that their favorite currency is 'backed'. There aren't any currencies other than gold itself that are backed by gold in that sense of backing, (with the possible exception of a negotiable warehouse receipt for gold). What they mean by backing, bitcoin has, and has done better.
The necessity of it is in the minds of those that think their currency is better than ours. The Bitcoin Specie project is to not only prove them wrong by example, but also to shame them for the fact that their currency has no Specie of its own with a value anywhere close to the value of the specie.
Come on, a $1 Silver Eagle oz? A $5 Canadian Maple Leaf? A $50 Gold Eagle oz? These are laughably wrongly denominated.