Speaking more about the mentality of things. A fighter can be wearing his Plate armor and just move up and out whomp things. No arcane failures, no spells to worry about, no songs, no non-proficiency penalties to avoid.
A newbie bard character, played in the same fashion has lower BAB, is using inferior damage weapons, is likely wearing more crappy armor, and will have fewer HP to work with.
With spells, twinkage and some skill, bards can kill butt with the best of them, if they choose to build that way, no question.