To avoid cables flying off in random directions. Same as Create.

should this apply in general with parts destroyed or only when using wrench
question is, will this have effect on other mods that use wrench support?

Oh yes, I should be more clear. I thought "dismantle" was clearly associated with using a wrench, but that's just what we call it in code 😓. I would only implement this if the player is holding a wrench.
Dismantling is always implemented by our blocks, not by the wrench itself. In short: It'd work with all compatible wrenches (currently wrenches are identified using an item tag).