This would make it difficult to impossible for ?teams? of riders to work together to help their best rider, but who cares? Teams are antithetical to all forms of racing except relays.
Somewhere after 50 years of tradition you quickly overcome objections that teams are antithetical to rall forms of racing except relays.
And the Chicago Marathon would have to be more like a bunch of 10 mile races over 21 days with steep climbs, sprints and cobblestones.
Only Americans would diss a legendary race that has more history than any major sports event in the US with the possible exception of the World Series.