My point is that if the Houses couldn't match those two BB classes(and most didn't even try), what would they possibly do in the face of a Lev, that is so far beyond them?
I am pretty sure that there is a table somewhere saying what tonnage the Houses could build when. Maybe IO.
In all fairness, you have to remeber that a McKenna or Texas are not in the same league as a Lev III. 200-300 armor can be dealt with. 1000 armor requires meta rules to not be invincible to everything except a near parity ship.
This is a what-if... the SLDF would have had the navy to escort a death star unit with far more effectiveness than 20 PWSs.
1000 points of armour is a failure or abuse of the rules by the original author. But that bridge had been already crossed by the authors of the Mjolnir and Avalon. It was pretty clear 300 armour was a lot in the existing ships. These ships took that convention and threw it out of the window. Arguably for the worse.
1000 armour does not require meta rules to defeat. This hue and cry did not follow the introduction of the Leviathan II, it was merely a challenge to overcome. The Leviathan III is not significantly different from the Leviathan II as a tactical unit. Armour is the same. Firepower is basically the same. It is harder to put a missile into. It is a little more accurate at long range, but you need to find a way to hold an enemy there. AA has received a boost. Armour is now Lamellor, to match the Odysseys and Hunters built at Alshain. The major change is those docking collars. But that is an extension of Star League doctrine and a lack/obsolescence of destroyers.
Now you might say that in 3070 the Houses had the ships to kill Leviathan IIs. Maybe. WoB and the FWL did. But no one else did and it didn't end the world. The Dominion and Combine fought a hot war and the big battleship was basically an irrelevance. WarShips are too easily avoided to keep the 'Mech dominant.
Now as for if the Star League built one? Well Potemkins exist don't they? Practically, if you don't want to use ASF or something, 3 modern Aegis will get the kill, probably mutually. So teams of Tharkads or Atreus could do the job, likewise New Systis can take the ASF approach. The big issue is not the inability to kill a single battleship. It is that the Hegemony could build 200 of them, and this is no different to a McKenna.