Dominion

Perhaps it's nonsense, but I'm not the only one who thinks so...

Losing a Castle is an unacceptable luxury.

When considering the risk of losing a town, the AI becomes completely passive. Its main hero doesn't want to go further than the garrison gates (and rightly so).

Further,

Why build it if it's practically impossible to hold?

It simply doesn't make sense to fully build secondary Castles – it's enough to partially build a couple of Castles and hold them with secondary heroes.

That is, no more than two Castles are built. One of which is already almost built (your own), and the second – “in this case… Necropolis” – is absolutely correct.
What “demand” for mines are we talking about if, at most, only two sets are needed? In reality, one set of mines is enough because your own Castle is largely built.

Stimulation to control lands, develop secondary heroes.

The map is controlled from the Necropolis; one secondary hero is needed there, who manages to intercept everyone who leaves the main hero. As a result, we have two mandatory heroes, and the rest are up to you. This arrangement exists for almost all standard maps.
With destructible Castles, losing the game flag inevitably follows the loss of the main Castle. By capturing any other Castle, it only gains illusory opportunities to win in the future. The AI correctly assesses all of this and simply gives up if it loses its main Castle. Is there any “full-fledged game throughout the entire match” here?