I think medical science may have on since the 1800s
While it has, not all injuries are equal
Different sport, mind, but pitchers in baseball treat getting a significant elbow injury requiring a surgery called Tommy John and 15 months of rehab as, in some cases, a good thing where the guy can come out the other side of it throwing harder than he did before. So many times teams won't shy away from this.
However, shoulder injuries are a different animal altogether. With significant shoulder injuries, so much can happen where they can't get velocity back.
In this case, I'd rather have a guy tear his ACL and think he can get back to 100%, whereas soft tissue injuries like a hamstring are harder to predict, and in some ways that risk always stays with you. I would definitely discount buying a guy that has had multiple hamstring injuries.