Why is disintegrate force damage?

My question is simple, why not necrotic damage? Since necrotic is about death and decay, it feels more fitting. Sure is sounds reasonable, you use fore to pull apart atoms, but then it gets weird, like its a single point, creature, or thing, so no explosion. Also it always converts it to ash. And finally, it doesn't move them, I'd imagine it's supposed to be a large beam that "rubs them out of existence", but in practice, it doesn't feel like that.

Force damage in this game is not at all related to pushing or pulling. It's not very well named at all really. From my reading of the various spells and effects that use it, I would define Force damage as a direct, violent attack on the soul or life-force of a creature - this being why almost nothing has resistance or immunity to it.

Necrotic damage might also attack the soul, but it is more a cold, draining, deathly attack. Radiant likewise, but hot and divine. Force feels more primal.

Disintegration is not trying to drain your life force like a vampiric touch, rather it is ripping apart the animating life energy of a being, and then the body falls to ash as a result.

That's just my way of thinking about it anyway. The real answer is it uses that damage type because the book says so... 

Force damage is basically just pure damage, and Disintegrate just destroys you, so Force is definitely the best fit.

necrotic damage is like your skin rots. The skin is dried up, shriveled, and mummified, but the skin is still there.

force damage, at least to me, always seemed like "destruction at the atomic level", like the atoms of your skin are turned to a gaseous vapor and float away.

I have always imagined Force damage to basically be non-specific magic damage. It isn't elemental like fire or lightning, and neither death and decay nor radiation like necrotic and radiant. It's just a pure magical force.