I think it is a bad thing in general. Most coaches, in all sports, think their sport is the most important. Kids are told that they should be multi-sport athletes, but the second that the other sport starts, kids get criticized for not being with their "team". This causes kids to burnout because they never get a break. And, if you have a kid that plays Baseball, Lacrosse, or runs Track, the majority of your football kids SHOULD be doing one of these sports, then what is the product you are putting out there for your Spring Football?
I can also see parent problem here. Kid A is the best RB on the football team. Kid A also runs track and is really good at that. Spring football comes around and he decides to focus on Track, as he should. Kid B, the back up RB, is a starter for Lacrosse and wont be able to attend Spring football. Kid C is not going to be on the field much, maybe 3rd string RB. He is the "starting" RB for Spring football. A lot of great chances for this kid to learn and be seen. Now, his parents expect him to start the season as the starter because he "started" in the Spring. Really crappy situation.