Because the focus on creating a narrative (story) collaboratively using the mechanics of a game. Just a wargames is a focus on achieving the victory conditions of a scenario, and tabletop roleplaying is about interacting with a setting as a character with their actions adjudicated by a human referee.
Now before you (and readers) thinking I am drawing hard and fast lines, it about focus. Focus is inherently fuzzy and readily adapted to hybrid forms. This can be illustrated clearly by the difference between Melee and The Fantasy Trip. Battletech and Mechwarrior. The former games are considered wargames, while the latter games are consider roleplaying game.
As they both use the same mechanics the only substantial difference is of focus. What you intend to do with the mechanics. In Melee the intent is to defeat your opponent(s) in a melee by achieving the victory conditions of the scenarios like last man standing. In The Fantasy Trip the focus is on pretending to be a character having adventures using the rules of Melee to handle combat.
In Battletech the focus is on defeating your opponents by commanding Battlemechs and other forces and achieving some victory condition. In Mechwarrior the focus on playing the pilot of a Battletech and while the system uses Battletech to resolve Mech on Mech combat it incorporate a lot of other subsystems and material not relevant to people focused on playing Battletech.
So it was with Blackmoor the first tabletop roleplaying campaign. By all the account I read, at first it would look and feel like an elaborate wargame campaign. While players were their character within the campaign, it was more of means to fight the larger battle of law versus chaos with both side comprised of players. But with advent of the Blackmoor Dungeon the focus and campaign shifted into something we would recognize today as tabletop roleplaying. Why? Because exploration of the Blackmoor Dungeon was a choice of the player as their character. It wasn't really relevant to the law versus chaos scenario. Ultimately it proved a distraction which lead to the downfall and exile of the forces of law. But it was so popular and so well-like that exploration of dungeons and ruins like the City of the Gods became Dave Arneson's campaign focus thus giving birth to tabletop roleplaying.
So with storygames, the focus is on collaborative storytelling using the rules of a game. Which values certain mechanics over other. Just as mass combat rules fell by the wayside and became a niche for tabletop roleplaying. It doesn't mean that there isn't overlap or hybrid system that straddle the line. As I said kitbashing previously I find kitbashing is the norm not the exception.
My view is that wargame, tabletop roleplaying, and story games lie on a spectrum. Yet each has a distinct focus. None of them are a 2.0 version of the others. Instead it represent increase in the variety and types of game.
So how is this theorycraft of any practical use?
The implication of my assertion is that rather than picking a game and then building a campaign. You decide on a campaign, what you want to focus on. Build the setting of the campaign whether it is wargame, roleplaying game, or storygame. Then pick the rules that best suits the campaign. One case it may be Blade in the Dark, another is may be D&D 5e, and another still it may be Shadowrun Crossfire. And you don't have to "pure". You can take a little from each game the only value judgement is whether detail makes the campaign your group want to run less work and more fun to play out.
I happen to be focused on having the players play as their character experiencing a setting. You may be more focused on collaborative narrative with everybody pitching in on a equal basis. With those as framework each of can work our group to pick or define a setting, and the rules we will play by.
Hope that clarify things.
My view it still a form of collaborative storytelling but one with a more competitive or resource bound aspect. The challenge is how can I create a interesting with my group given the resources the system given me. The resource being some type of metagame mechanic or currency that player not the character can do. Or maybe it a zero sum setup and more competitive. Like I said all sort of hybrids are possible.
However in traditional roleplaying because of it focus, players don't expect to be able to something that their character can't do. The game you describe, the player can do more than what their character can do. From I seen
As player you have mechanics at your disposal
Competition can be a form of collaboration as far as the end result goes. Look at places of natural beauty like rain forest. Definitely some competition there but yet the result is something complex that defies the laws of thermodynamic.
Wrapping it up.
If you think I am an old gamer talking weird naughty word, I am not offended. I well aware that my view are not shared the mainstream or many of the niches of our hobby.
I believe my view has a practical application help people produce campaign that are fun and interesting to play.
- Figure out what you or the group want to focus on for the campaign
- Make a setting for the campaign
- Create or collect the rules need to make the above happen.
- Play
Note that nowhere I am saying
how to play the campaign. Just pick whatever make it work the way you and your group wants to work.