Physical/magical damage reduction differentiation should be removed

[Daeriion_Aeradiir]

Uhh, almost every raidwide is magic. Almost every tank buster is magic.

Maybe in the past, but EW has been mixing them quite a bit more.

Harrowing Hell, one of the hardest hitting raidwides this game has seen in a long time, is physical. P1s's more spammed raidwide is also physical.
This tier alone has physical tankbusters in every fight. (And for P11s & P12s pt2, they're only physical, whereas P9s, p10s and P12s.pt1 have one of each)
P5s had a physical buster along with a magic one. P6s had a stack physical buster, and one half of the forced swap buster was physical.

Two of the EX trials had physical busters.

Point being, that statement is far from accurate these days.

Is it... that bad that an RPG asks you to differentiate between 2 simple concepts for a paper-thin amount of immersion?

While it's far from confusing, it's also not even a paper-thin amount of immersion either. The vast majority of mit in this game is omni-damage at this point. Two of the four tanks (PLD/WAR) literally have full omni damage mitigation, GNB only has partial damage type on one single skill (camo), DRK is the only tank that has a true 'one damage type or bust' self mit. On the raid mit side you have a grand total of 3 skills that still adhere to damage types - Dark Missionary, heart of light & Fey Illumination afaik. Addle & Feint technically have damage adherence, but they now affect both damage types so they can be more freely used regardless of damage typing.

At this point, damage types may as well not exist outside of a mechanic giving magic vuln+ / physical vuln+. You could change the remaining holdouts to pure damage % and literally nothing would change in the grand scheme of things.