Rough consensus relies on the distinction between two types of objections:
“Not the best choice” feedback: “I don’t believe Solution A is the best choice, because XYZ. I believe Solution B would be better, but I accept that Solution A can work too.”
Fundamental flaws: “I believe Solution A is unacceptable because XYZ.”
A chair who asks, “Is everyone OK with choice A?” is going to get objections. But a chair who asks, “Can anyone not live with choice A?” is more likely to only hear from folks who think that choice A is impossible to engineer given some constraints. The objector might convince the rest of the group that the objections are valid and the working group might choose a different path.