What's wrong with foil? Oh..I don't know...It's completely incapable of causing injury? It's physical properties distort the physical reality of real swordfighting?
You're ignoring the obvious fact that the foil itself is a practice weapon, and thus it is not designed to "cause injury" in the first place. That's why the Italians called it the spada d'exercizio.
However, you should also note that the Italian foil is very close in form to the Italian duelling sword, which is indeed needle sharp and thus capable of killing.
Likewise, foil technique in general (Italian or French), can indeed translate well to actual, functional swords--smallswords, spadroons, sabers, etc.
As for your claim that the foil's "physical properties distort the physical reality of real swordfighting", that only applies to the foil's flexibility and the corresponding use of silly, bastardized moves like the modern "flick attack". It certainly doesn't apply to the foil's light weight--and anyone who claims otherwise hasn't actually handled a real smallsword or duelling epee.
And the rapier blades, being so narrow and of so small substance, and made of a very hard temper to fight in private frays... do presently break and so become unprofitable. --Sir John Smythe, 1590