The better quality with DLSS is real! It cures the shimmering also.
I am experiencing this too and I don’t see any significant blur added to the aircraft displays.
See this screenshots extremely magnified:
Of course the screen resolution should be high enough (in my case 3440x1440) AND you have to select DLSS Quality. The other modes are aimed to help the weaker RTX cards.
You cannot ask 1080p DLSS Performance to be good!