Why does dispell remove friendly buffs?

[Xargon]

Originally Posted by Handel

Besides the goblin shaman spell "Leech of life" or something like this

You can dispel it on an enemy troop that has at least one other buff/debuff. It just does not show up as a viable target if it has only threads of life on it. So a workaround is to cast an auxiliary debuff at the enemy unit and the dispel it (not sure about dispel lvl3, it works with lvl2).