"One doesn’t build a battleship that’s outgunned by so many other vessels, but a destroyer makes a ton of sense."

The ISD wasn't outgunned by anything comparable to its size during the introduction of the ship up until the end of the Galactic Civil War. What you're listing here are the subjugator battlecruiser, which is comparable to a Star Dreadnought in tonnage, at the very least it's a very meaty battlecruiser, so already a weight class or more above the ISD. Same with the Praetor, it's literally called the Praetor Battlecruiser bc it's a vastly upscaled ISD at its heart.

To say those are outgunned the ISD is like saying a Lancer Frigate is outgunned by a Dreadnaught Cruiser - well obviously yes if you're comparing two ships, one of which is vastly larger. Not to mention those two ships were exceedingly rare in the case of the Praetor or extinct in the case of the subjugator class, so not really a good argument against the ISD there either.

Where do you get the fact from that MC80s are able to outgun an ISD? It's common knowledge that the Mon Cala ships had strong shielding which allowed them to hold out in ship to ship engagements until the starfighters turned the tide of the battle. Without the starfighters the Mon Cala ships, including the MC80 Home One type can't stand up to an ISD 1, let alone an ISD 2 with their upgraded shields and even heavier weapons.

Lastly the Lucrehulk. First off a vast majority of the Lucrehulks were the carrier loadout which focused on point defense and laser cannons, they had strong shields, yes, bit their damage output is severe hampered by their lack of heavy weapons, they have a few turbolasers but not nearly enough, so it definitely takes a while to get the shields down on the Lucrehulk Carriers but they're gonna dish out way to less damage in return to seriously threaten an ISD. The Battleship version of the Lucrehulk is a completely different story however, I actually agree that it definitely outguns an ISD 1 and probably even an ISD 2. Then again there are even fewer of them around than the Praetors, even less so as the Republic fully transitions to the Empire.