they did said they can have comebacks without all the members, they didn't said the members will miss promos as full group, at least SM can balance their activities between groups, nobody said Mark or Haechan to miss a 127 comeback, Dream will never have more than 1 comeback per year either way but they can miss some events for them to attend Dream, obvious a concert is more important in this case but in general SM is obvious favoriting 127 over Dream, at least they can annouce when members are missing, not the first time SM has done it. Dream ended like this because of SM's incompetence, the system should never happened in first place and the members should never be in 2 units unless is NCT U, SM is always bitting more than they can chew and the artists are always the ones losing.
This is the reason why i stopped stanning NCT even if i liked some songs, my blood rise everytime i see how they blatantly favorite a unit over the others, they don't even try to hide it. I never saw a company being so fucking obvious that they don't give a shit about one of their newer artist, especially a bigger company, you can also include WayV there which i feel extra bad for them.