TR - I do get the development aspect and in a perfect world, where kids don't move, get injured or burn out, it works out great. That is why travel teams are easier to Coach - because you have control. HS you do not have that luxury. This kid may decide he loves it at this school, because his baseball experience was great, you just don't know. That is why I think you keep the best.
You can't rely on the kids being there from year to year. The point is, HS Coaches have no control over who will stay, go, or if the the next Bryce Harper will be moving into the district. So you work with what you have from year to year.