Necropolis or Castle (Which one is stronger?)

Diplomacy..., creatures..., abilities... - all of this is a waste of time on unnecessary statements in favor of one castle or another, because, let's face it, the main strength of Necromancers is MAGIC, and not construction, vampires, cheap units, etc. The only thing is that this feature, like this secondary skill, is quite accessible to any of the castles, and not just humans. What prevents you from having the ability to recruit skeletons while playing as completely different factions? The only drawback is the absence of an extra 10% Necromancy and the existence of only unupgraded skeletons..., but all of this is not very significant..., IMHO.