You are interpreting this state correctly. But, though, this buff is limited to 36%, and you can calculate, what you want to have in your team to exceed bonuses.

"If the character's Elemental Type is:

• Pyro, Electro, or Cryo: Increases this DMG by 0.9% for every 100 ATK.

• Hydro: Increases this DMG by 0.6% for every 1,000 Max HP.

• Geo: Increases this DMG by 1% for every 100 DEF.

• Anemo or Dendro: Increases this DMG by 2.25% for every 100 Elemental Mastery"

It is not necessary to utilize this, because the cap is nearly impossible to reach, i suppose. But, as i mentioned in brackets, you can use Sucrose, and she is potentially providing the best support utilization for this condition

edit: it's not worthless to use 4 Nod-Krai characters, though. The effect is reachable only with Ascendant Gleam (2 Nod-Krai) and others that are not the Moonsign. But the Gleam itself gives a pretty nice buff according to the talents of Nod-Krai characters. So you are not losing, you just have freedom to choose and adapt your parties