Hezbollah is tied down in Syria fighting for Assad, and has lost a lot of troops even though the survivors are now combat experienced. But Hezbollah needs troops to deter an Israeli ground invasion in order to have the time to bombard Israel:
Hezbollah has a nasty collection of more than 130,000 rockets, missiles, and mortars aimed at Israel. ...
In Hezbollah's arsenal are about 700 long-range, high-payload rockets and missiles with names like Fateh-110 and Scud D. They are capable of taking down entire buildings in Tel Aviv or Jerusalem, wreaking havoc at Israel's major military bases, killing thousands of Israeli civilians, shutting down the nation's airports and ports, and taking out the electric grid. And that's just in the first week.
While the article rightly notes that the legal responsibility for civilian casualties when Hezbollah weapons are located near civilians lies with Hezbollah rather than Israel when Israel strikes the weapons, the problem of knocking out all those weapons quickly is a separate issue.
The article doesn't dwell on the ground war aspect, but they do say a ground war will be required (and don't even mention the UN, which failed to prevent the stockpiling of 130,000 rounds of ammo). Yet it paints a picture of Hezbollah strength:
Iran has supplied its favorite terrorist organization with other top-of-the-line weaponry. For military aficionados, these would include the latest guided, tank-piercing Russian-made "Kornet" missiles, SA-17 and SA-22 air defense systems, and even the "Yakhont" class surface-to-ship cruise missiles. Making matters worse for IDF planners, Hezbollah boasts a standing army of more than 10,000 soldiers—a figure that could add two or three times that amount of reservists in the event of a war with Israel. In short, since its last major conflict with Israel in 2006, Hezbollah has dramatically increased its combat capabilities and armory.
Israel has worked to improve their ability to fight on the ground, demonstrating capabilities against Hamas that could be used against Hezbollah.
But the air-only faction may argue a more recent war is the model.
And remember that Israel's Iron Dome system isn't designed to protect civilians and the limited ammo will run out rather quickly. Iron Dome can only mitigate the threat of Hezbollah bombardment and buy time for Israel's military to end the threat.
I believe that air power is insufficient to end the bombardment before Iron Dome runs out of ammo (or before the small amount that gets through even an unlimited supply of anti-missiles hits a densely populated target).
Therefore, a ground invasion that goes all the way to Baalbek, Lebanon will be needed to really rip apart Hezbollah.
The article I cite makes too much of Hezbollah's ground capabilities. Even 30,000 light infantry isn't too tough for the Israelis to defeat. Especially when you consider so many are in Syria (which isn't popular, and their casualties have been heavy for such a small force as I note in this post).
Even the combat experience Hezbollah fighters are getting in Syria against rebel light infantry won't prepare the Hezbollah troops for the shock of a mechanized and airborne offensive well supported by precision firepower. If the Israelis fail to move fast and deep, that experience in Syria will come in to play if the Hezbollah forces survive the Israeli attack and adapt to the new type of fighting. But initially that experience will not be fully usable.
The Israeli military has been able to wage decisive military campaigns against other large mechanized armies. Defeating Hezbollah's relatively small amount of light infantry should not be a problem if Israel truly decides to wage a serious ground campaign against Hezbollah rather than hoping air power used more rapidly and efficiently can deal with the rocket problem.
Israel shouldn't let Hezbollah's ground force deter the proper use of the army. In 2006, that attitude led to Israel screwing the pooch by failing to properly use their army.
And a decade later, Hezbollah's bombardment capabilities are far greater.