It’s one of those interesting things that reminds you that the system is written by coders, who number lines of code by 10’s in case they have to squeeze something in there later. For operations (on jobs) it can be necessary if you have to add things in between. For materials, maybe not so much, but they kept the convention.
also, if the numbers in the engineering workbench won’t line up with the numbers on a job. Materials usually do (depending on the circumstance), but assembly sequences can’t with more than one level. So I wouldn’t get too hung up on making them match.