Good coaches don’t rush out contracts because they trust that parents/kids won’t leave. Why would anyone want to leave a good coach?
Good coaches also know that retaining good players is important. Good players typically have several options and aren’t going to wait till tryouts to know if the coach is bringing them back next season or not. So settling contracts early is a win-win for coaches and players. Players know where they stand and if they need to find a new team. If they need to find a team knowing it in Feb gives them time to find a good match. Coaches know who stays and can be proactive in bringing in new players to fill spots.
I know earlier in this post someone bragged about waiting till tryouts because their kid is this good. Believe me, no coach wants to deal with this kind of uncertainty in March.