Had a real hatred of "favored terrain" for rangers.
Now, in your usual game, where the characters may be bopping about the world from desert to mountain to city and then to the Elemental Plane of Fire, yes, it's a weakness.
With any degree of realism, it's immensely useful. A ranger would team up with a druid, a rogue whose talents turn on scouting, and a wizard with the right spell set, and they would fight monsters in the woods. Specialties would not just be having someone who could cope with anything in the party; it would be parties that winkled out bandits or goblins, or ones that fought dragons, or went through the city rousing out the evil enchanters' guild.
That this helps unify the Gamelit novel is an added bonus.