Changes happening in time are probably the most typical cause for the need of SCM. It is probably not a good idea however to give precedence to this viewpoint.
SCM builds its understanding by making software configurations comparable to one another. This is done independently from whether these configurations have been produced in sequence or in parallel, and whether they are even intended to map onto one another or to differ (e.g. are variants).
Let's keep the metaphor of relativist space-time in mind: time is local.