How many people do you think have never had a common cold? This is no different.
Actually, COVID can be a helluva lot different from the common cold. Now I didn't check to see how many of these guys are asymptomatic; if they have no symptoms or have mild symptoms, then no problem. But if they have it bad, it can be dangerous.
I believe the big thing will be that any player regardless of symptom status will be out of commission for and unable to play for a period of time; the asymptomatic will have to quarantine for 2 weeks, for example. Some with symptoms -- a bit longer. This could have a negative impact on the teams' performances this season.