Afterlife/Mirror March Discrepancies

TheDude1

After watching Matthew's excellent Orzhov Pontiff video here:  <a href="https://forums.d3go.com/discussion/77964/check-out-goblinpiles-video-channel-bonus-video-included">https://forums.d3go.com/discussion/77964/check-out-goblinpiles-video-channel-bonus-video-included</a>

I noticed that Mirror March treats reinforcement removal different than any other process.  It counts each reinforcement removal individually, even though they happen all at once. 

Afterlife's description is that "When this creature dies or loses a reinforcement, create X Orzhov Spirit tokens, where X is this card's afterlife".  There's no mention that it counts how many reinforcements are lost, only that it triggers when the event (death or removal) happens.  If the reinforcements all go away at once, that is just one trigger of Afterlife, but Mirror March is acting differently.

To use an example, if you destroy a 2x reinforced creature with Afterlife 3, you only get three spirit tokens even though there were technically three creatures destroyed.  But if Mirror March removes the reinforcements, it creates 6 spirit tokens, even though the removal only happens in one step.

Why does Mirror March's removal count differently than every other process for Afterlife?  If reinforcement counts matter for Afterlife, why only for Mirror March and not other effects?