The Project on Government Operations observes that the top brass arrive to testify before Congress with a pack of aides. They're critical, as well they might be. Their point is there are too many generals and admirals in proportion to the grunts.
However there's a counter argument, which may not apply to testimony before Congress but can apply to attendance at meetings. One of the best things I think a manager can do is to highlight the contributions of subordinates. If a manager brings staff to a meeting, he/she should often be able to have the staff person do the talking and arguing. I was able to do that sometimes, though often my know-it-all tendencies interfered. :-(