
Originally Posted by
Seraphor
It's not just because "it's forbidden", it's because of why it's forbidden, and of how it clashes with established lore.
BLM is about draining aether from your surroundings to create extremes of energy, extreme activity (heat/lightning) extreme inactivity (ice). This act attracts Voidsent, and was then used to directly summon Voidsent. These Voidsent were used in the War of the Magi by the Mhach.
WHM is about using the aether of the elementals, drawing like-for-like aether from the surroundings in order to summon and mobilise matter; earth, water and wind. This 'mobilising matter' was ultimately used by Amdapor to great golems and animate statues like the Kiribu.
They were 'forbidden' due to the war, because these techniques were used to such an extent that it drained the land of aether and knocked the elements out of balance, causing a Calamity.
Necromancy on the other hand isn't just 'forbidden because of possible repercussions or effects', it's sacrilegious, it involves desecrating the dead, it's offensive to the people of this world.
The difference between these two things, is like the difference between burning fossil fuels, and grave digging.
Being a necromancer in Eorzea is like walking down the street wearing a red armband with a swastika on it. While being a BLM or WHM would be kinda like being the only person trusted with the nuclear launch codes and knowing when to use them, except that it's possible to use them in smaller amounts for practical means.
Edda went insane in her quest to resurrect Avere, and in doing so, created a soulless monstrosity whose only purpose was to cause more death.
I just don't see any way of reconciling this in a way that a Warrior of Light could utilise.
Straight up Necromancy is a despicable act.
Summoning Voidsent is what BLM's do, so it conflicts with an existing jobs lore.
Creating aetherial simulacrums and imbuing them with agency, is what SCH/SMN does, more lore conflict.
And in general, summoning pets to fights is what SMN does as well so it wouldn't even be a unique job mechanic.