No, the change does not only impact soccer. CIF changed dates for many programs (fall through spring): https://www.noozhawk.com/article/prep_seasons_will_start_end_earlier_in_2018_19
Soccer is a winter sports in So Cal because Football is a fall sport (nobody is changing this) and Track/Field and Lacrosse are Spring sports. If soccer were to move to Spring then Track/Field and Lacrosse would need to switch to Winter. Consider that schools generally only have 1 field/stadium. Teams need to practice and share resources. Football uses the fields/stadium almost exclusively in Fall. Football is the 800 pound gorilla because it makes money (sort of) for the schools. Once football ends, soccer (boys and girls need practice field and game space) which is exactly the same spot for most schools that football just left. Once soccer ends, the track and field and lacrosse teams need field space, which is the exact spot that soccer just vacated. In fact, its not unusual to be playing a JV soccer game in the stadium and have the track and field team on the track warming up/practicing (an annoyance).
Because soccer can be played in the rain with little danger, whereas, track and field should not (more dangerous with certain events) ... winter it is.
Soccer is a winter sports in So Cal because Football is a fall sport (nobody is changing this) and Track/Field and Lacrosse are Spring sports. If soccer were to move to Spring then Track/Field and Lacrosse would need to switch to Winter. Consider that schools generally only have 1 field/stadium. Teams need to practice and share resources. Football uses the fields/stadium almost exclusively in Fall. Football is the 800 pound gorilla because it makes money (sort of) for the schools. Once football ends, soccer (boys and girls need practice field and game space) which is exactly the same spot for most schools that football just left. Once soccer ends, the track and field and lacrosse teams need field space, which is the exact spot that soccer just vacated. In fact, its not unusual to be playing a JV soccer game in the stadium and have the track and field team on the track warming up/practicing (an annoyance).
Because soccer can be played in the rain with little danger, whereas, track and field should not (more dangerous with certain events) ... winter it is.