The purpose of all this is to avoid the appearance of collusion, or seeming to obstruct anyone from participating. All IEEE working group meetings are open, and anyone may attend if they are interested. This principle must be employed for every official IEEE meeting. Any person has a right to attend and contribute to IEEE standards meetings. That way, they are available to anyone who asks for them.
Openness also provides protection against antitrust situations.
Since standards are so broadly used and often carry the weight of law, it is important to allow all parties to participate and be heard to avoid a situation that would imply that any company or individual was restricted from speaking. Both of these principles should be considered from the very start of your standards process.