Sure, and most of the times it is indeed like that, just jamming and that's it. But then there are things like 'Innuendo' or 'Under Pressure' as well.
John hated Hot Space. Frederick's favourite singer was not Paul Rodgers. Rog didn't compose 'Innuendo.' Witness testimonies are often inaccurate. Wales is not in England. 'Bo Rhap' hasn't got 180 vox.