MBN, Well I can understand this. Basically if you're fleet is such much smaller and dies while dealing 0 damage it auto generates it. This reduces server load.
Game play wise it makes sense as I'm sure some of you have killed pirates or something with such overwhelming force your first volley kills everything at a range greater than the enemy ships so that they don't even return fire.
Gameplay wise, this prevents people from skipping espionage tech and just spy/probing am enemy with 1 unit. Ie, fighter, scourge, etc. To get full fleet information from combat report (fleet numbers. Upgrades, etc) when normally their spies would not be capable of it or would require a significant amount of spies being sacrificed which are not cheap relative to 1 combat ship
that is not possible = Alien fleet (11 Large cargo) of a player xxxx sent from planet Sirius [xx:xxx:x] with mission "Attack" was torn to shreds near planet New [xx:xxx:x], due to huge power.