Which is stronger, a Castle or a Conflux?

1) It's not entirely clear where these conclusions about the hero's level come from.
In online games, hero levels are usually as follows:
1-1-7 (6-9)
1-2-7 (12-20)
1-3-7 (18-21)

2) The final battle is a subjective concept. (Large doesn't always mean final), but for me, it's always with the main hero. If you're caught with a large army not with the main hero, then that hero becomes the main hero.

P.S. In online games, merging is highly valued because it allows you to learn what you need in the middle and at the end of the game (and especially at the start).

I drew my own conclusions based on your posts, that online games often end quickly, i.e., the actual game time isn't very long, so you won't reach a very high level... Now I understand more or less. (especially since you yourself say: "large doesn't always mean final").
Regarding the finale, I understand that in principle, but I think it's not uncommon for games to end in such a way that the main forces are not available (the hero is too far away, or there's a siege of a castle captured by the enemy).

P.S. It's nice to have a dialogue with someone who is tactful and articulate, and doesn't try to prove anything, but simply expresses their point of view... :)

Sincerely.