Inviting only people who support and agree with you to a meeting seems like a great way to run a company.

It depends on what the meeting is. There are situations where you might not agree with decisions being made, but undermining your superior infront of business partners is not ok.

Those are the kinds of problems you handle privately. Not in a meeting with other people from other companies.

Yep and now you are committed to something you didn’t want to be committed to because you couldn’t say anything in the meeting.
You always talk before a meeting to decide what is going to be decided in the meeting.
That is assuming you have sane environment and processes, which is a bold assumption for a lot of people
Wouldn’t you need to talk more before, if there is no sanity?
You seem to expect the person you talk to would listen, it’s not always the case, unfortunately
The Expert

You were probably already committed to it long before the meeting started.

Time for objections and concerns have already passed