I thought the same. Just prime well and if necessary paint twice with good paint. That was my plan. I actually didn't want to sand the entire surface anymore.
That is exactly why the primer is necessary to prepare substrates of virtually any kind for painting. You only need to sand the plaster if you want it to be particularly smooth.
I'll take the risk without sanding this time. Theoretically, I could also apply wallpaper or fleece on the primer without sanding the entire surface beforehand? I'm still considering how to proceed in the children's rooms. And for HAR and Co, I'll initially stick to my original idea of priming and painting the plaster without sanding beforehand.
Thank you for the numerous responses..... Apparently, I am not the only one with the "problem"
You only often read:
No dispersion paint, because it is not breathable and promotes mold growth. And the utility room is rather too humid (washing machine, dryer) than too dry.....
Tiefengrund is plastic soup. You don't need to worry about the dispersion anymore.
Even dispersion paints and primers label themselves as "(vapor) diffusion open" or "diffusion capable." As long as it doesn't seal the wall 100%, these statements are even true.