Actually they may have accomplished a lot. The problem is nobody's publishing casuality figures for Hezbollah.
The Katyushas, for example; those things aren't exactly stuff you make in your backyard. How many has Hezbollah expended, what was their total supply? You launch them off the back of trucks; how many of the trucks are left, and how many of them got blasted by IDF aircraft or artillery? The mechanics who keep the trucks running?
Furthermore how many years of recruiting has the set back Hezbollah? Everybody else who's fought the IDF has gotten mauled; there's no reason to believe things were any different. They've probably lost hundreds of people; perhaps more. It will take years to make up their losses from the IDF...and they're not exactly out of the woods yet.
And how many people do you think are more willing to join Hezbollah now? The whole point is that
any terrorist or insurgent network gains support from engaging a larger foe; it's very much the 'plucky underdog' effect that gives them strength, allowing the justification of the likes of terrorist attacks as a response to an inability to fight symmetrically. Terrorists aren't measured in military strength; they're measured in their ability to operate within a civillian population, and with the tacit support of that population. I don't think Israel has done anything to erode that support base - I'd say history proves the opposite will occur, with short term losses being recuperated by the desire for revenge in South Lebanon.
Plus, the likes of Iran and Syria certainly won't be any more scared to provide military and financial resources to Hezbollah; they've proven themselves a very useful proxy in this war by 'forcing' the IDF to kill hundreds of civillians and significantly set back the Lebanese democracy whilst still failing to wipe out Hezbollah (why else would they be continuously escalating the IDF presence & actions right up to the point of ceasefire?). I can't help but think this war has been nothing more than the futile pissing away of lives on both side -
yet again.