These larger to manage role playing groups have harder to manage groups. Special privileges usually need to be established to avoid talking over one another. Dungeon Master’s must usually wear the “I am DM and you will listen” hat. Groups can survive without these steps. However, serving the needs of the Dungeon Master makes for survivable adventures as many players have witnessed firsthand.
These adventures are cumbersome for skilled Dungeon Masters and they are bordering the ‘unmanageable’.