Infernal Legion Support Gem Not Stacking

The Infernal Legion Support gem offensive fire damage does not stack for each minion affected by it. A "Legion" is multiple soldiers for war, not some kind of turn-based battle where only one soldier can do damage at a time. Has GGG addressed why this does not stack, or if this is intended behaviour? Thank you.

Bug Report Reference Number: 4,074,915,212

Infernal Legion applies a damaging debuff to enemies near supported minions, and the same debuffs don't stack in poe (unless the debuff is stackable by design like Poison or Blight).