OBJ files can include groups of faces. A group is basically a cluster of polygons to which you assign a name. For example, V4 has groups called lForeArm, rForArm, lShldr etc.
To create groups you load the OBJ file in a mesh editor like Blender, highlight the polygons beloging to the group and the assign the name of your chosing. You then save the OBJ with the option to preserve the groups. When you load the OBJ in the FST the tool will automatically recognize the groups and it will be able to create the bones from there.
What I meant with "not a requirement" was that the FST is not imposing that rule, it's part of Poser's standard, the FST is just following that standard. You would be required to create groups in Poser as well. With the difference that Poser's group tool is much, much more limited than what you have in Blender or other high-end modeling tools.

Cheers.

Paolo

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