But they didn't until the season was done. Because it's strategically disadvantageous. Draisaitl is also not a bigger star than Matthews, but that's besides the point.
Yeah. Different players are different, and have different preferences around their medical information. Different injuries are different, and require different precautions and secrecy, and there are different medical timelines and certainty in timelines. If the team isn't saying anything, then it's either out of respect to Matthews, or to prevent a strategically poor disclosure. There's no reason that you have to know.