A brokered convention is actually an open convention. There are no longer any brokers...
You’ve completely contradicted yourself...
In 1976, for example, uncommitteds decided it without need for ‘brokering’.
You could just as easily say they decided it without ‘contesting’ as Ford won on the first ballot, and there was no floor fight...as to whether there were any back room bartering, who knows...
You can assign your own private meanings to all the words you want. Others will not necessarily go along.