It is an opportunity for you to get important feedback about aspects of the plan you might be under-informed about and make sure the relevant parties are aware of what is happening.
After feedback, you may decide your plan was flawed and needs adjustment, but just because there is disagreement doesn't mean you need to change your design to fit everyone's needs.
An RFC should seek to articulate the key constraints, surface every unique point of disagreement, and address every one of those. Sometimes, addressing such a point may involve changing the proposal; other times, it'll involve providing a considered and thoughtful response that amounts to "no, and here's why not". That may lead to someone dropping the objection on further consideration, or refining their concerns in an effort to better articulate what they value that they feel the proposal doesn't deal with. And occasionally, even after that, the answer may remain "no", and the objection will stay on record as disagreement with the consensus.
This point is mentioned but there's no clarification. As soon as you open up a design discussion to other members you're heading to design by committee territory, unless you take specific action to control it. Is there something in the formalized RFC process that addresses this?