The entire modern sport of cycling is based around the idea that riders sheltering behind forward team mates or rivals burn much less energy pushing through the air.

Without the rules governing bike design riders would probably gravitate to the use of fully faired recumbent bikes and the team dynamic would be lost. We'd be reduced to what amounts to individual time trials.

This is one reason why we have individual and team time trials on slightly less restricted designs to separate the desciplins.