It would be so unfair; even if a team doesn't game the system if it loses, say, three domestiques in a crash half way through the race and is able to replace them it still then has a great advantage over other teams, especially the ones with riders who are not that badly hurt they can justify being subbed.
And, again, riders want to finish so they would be more likely to carry on, pretending they are ok and not getting treatment, because they don't want to be subbed. It would have the perverse effect of making some riders decline treatment and end up worse than they are now.
It would be so unfair; even if a team doesn't game the system if it loses, say, three domestiques in a crash half way through the race and is able to replace them it still then has a great advantage over other teams, especially the ones with riders who are not that badly hurt they can justify being subbed.
And, again, riders want to finish so they would be more likely to carry on, pretending they are ok and not getting treatment, because they don't want to be subbed. It would have the perverse effect of making some riders decline treatment and end up worse than they are now.