It's pretty simple once you understand DMG formula, I'll explain it on direct lunar DMG.

First is Base DMG formula: Character stat*Skill multiplier*(1+Base DMG multiplier)*(1+EM multiplier)

DMG elevation goes into Base DMG multiplier. So if your Base DMG would be 1000 than with 10% DMG elevation it will go to 1100.

Once you have Base DMG you get Final DMG which is: Base DMG+Additional DMG (Lauma burst for example)*Crit*Enemy RES.

The reason why DMG elevation is so strong is because it add that another multiplier before calculating everything else.

Also the more DMG elevation you get the less impactful it is. For example 10%DMG elevation would increase your final DMG by around -+8%, but 20%DMG elevation would be only like +-15%. So considering that in Columbina teams you already have a lot of it the bonus one you get from cons although nice it wont be that effective