This system has several advantages:
You can specialize easily.
You don't automatically lose the subskills if the parent gets worse.
The parent actually has a use once it's subskills are learned (which is
currently a problem with magic)
The assist problem is cleaned up, since if the assistants have the general,
they get a precentage of its skill, or they can be trained in the specific
skill by the one they are assisting.
You don't have a base chance of using a high level subskill when you get it.
Additionally, you should be able to try to use 0 level skills (though 0 in a
base skill would give you 0 chance to complete and abort, if you had 10 in
entertainment and a 0 in street mime, you would have a effective 5(or whatever)