Tournament preparations!

I don't see anything wrong with this. You could just as easily say, "Why hold a Heroes tournament?" Tournaments are held for games like Space Rangers, for example.

No, there's no need to confuse the two.
You're comparing a game with a good multiplayer mode, which, in my opinion, is designed specifically for playing against other people. That's why regular games in Heroes turn into tournaments, that's why Heroes 5 has a Ubisoft server designed for games between people, and so on. There are many such games, and not only in the fantasy genre, but the difference between them and RPGs is that the latter are designed for the story and single-player mode. For example, Oblivion only exists in single-player mode, and the ability to play it as a team is only available in a patch.

King's Bounty is still a game for one person; it's more of an RPG. Therefore, holding tournaments for it is like wanting to compete in everything :) Maybe some people like it.
That's just my opinion.