I was watching a clip of "Chicago" playing a song years ago. Bands aren't true musicians like before, are they?

These guys were playing horns, all types of saxes (alto, tenor), guitars, etc. Peter Cetera was holding down the b while doing lead vocals. Today bands just sing and dance while hiring musicians to play the real music it seems. Am I wrong? I think it's so much better and higher quality the old way, with musicians instead of performers. Any thoughts?