On a fairly regular basis, when we invite to dream together, there is a handful of people annoyed by the whole exercise. They describe it as a waste of their time, irrelevant to their work.
What I'm always curious about is their relationship to existential guilt. I think people who can't tolerate the anticipatory guilt of not fulfilling dreams will resist dreaming in any way they can.
Should we excuse them from dreaming. I think it's OK to ask them to come back when we're doing questions and actions. They're going to see the dreams of the whole and work in alignment with them.
What helps is reassuring them dreams aren't goals. This assuage their guilt and opens space for the possibility of dreaming.