The discussion becomes clearer when ideas are considered before their owners are ranked.

Rooms tend to evaluate the speaker first and the suggestion afterwards. Once you know whose idea it is, your sense of whether it is any good has largely been settled, and the discussion becomes a way of confirming the existing order rather than finding the best answer. Good thinking from a junior or unpopular person is the first thing lost this way.

In your next meeting, try holding the proposal up on its own before anyone weighs in on who made it. Ask what would have to be true for it to work. If you notice yourself dismissing something quickly, check whether you are judging the idea or its author.