Explosive balloons as an air-defence proposal

Were other air-defence ideas so bad that unrotated projectiles appeared effective?

Suspending impact-detonated explosives from hydrogen balloons over cities is offered as a hazardous comparison, without endorsing unrotated projectiles.

One proposal adapted the spar-torpedo idea by hanging impact-detonated explosives from balloons tethered over a city. The balloons were to contain hydrogen. Falling balloons and suspended impact detonators would threaten the population the system was supposed to protect. The proposal was Italian, although Britain also examined it. This hazardous alternative gives no reason to conclude that the unrotated projectile was effective.