There are only three gaming cultures

 Those who joined the hobby from playing board games, those who joined the hobby from playing video games and those who joined the hobby having played no games.

Some establishing information

Wargaming, as it existed before D&D (excluding Braunstein-like material) could be considered a subset of the board game hobby.  That is, from at least one key viewpoint: the players involved read the rules, and followed those rules.  As well, the boardgame hobby tends towards trying out new games, often every week (this from observation), and the wargaming hobby, again of the late 60s/early 70s seems, also from observation, to have been similar in this aspect as well.

The thesis

1. Those who played the game at its inception were those individuals drawn from the war-game hobby.

2. Due to the advancing popularity of video games, at or around the 1990s and culminating during the 3rd edition of the game, those who joined the hobby came from the background of playing video games.

3.  Starting with the 5th edition of the game and gaining full momentum post 2017, the flood of new players joining the game, drawn primarily from Critical Role and Stranger things, were those who came from the background of media consumption as their primary "hobby."

The effects

Those who were from the boardgame/wargame hobby read the rules and followed the rules, playing within the bounds of the game, creating a game where the results lead naturally from point to point, gold gained from the dungeon funds castles, castles are used in war, empires rise and fall from these wars, a campaign is played all the way from the local scale to the global scale.  Idealized, I know.

Those from the video game hobby sought to break the bounds of the game, seeking freedom from the constrictions of the rules, to do things not described in any rule book, not covered in any setting book and not managed by any government.  These players find the dungeon useless and never return to it once it is left behind.  Kings are felled by plots so ridiculous that they can't not work, intercontinental travel is found in the first week, interplanar travel within a month, and interplanetary within a year, if the game lasts so long.  These are the power-gamers and min/maxxers, those who will do anything the rules allow because the rules allow it, because it is precisely this that they find to be fun.

Those who joined the game who were raised on media and content creation seek the unknowable, rules are a plague upon fun to these individuals, they do not care what the rules say or do not say, they do what is "lol random." They want to have social interactions with every tavernkeep and provendor of goods, they want to role-play shopping.  Internet-infested minds, incapable of sophisticated thought, nothing more than crawling beasts wearing human skin, they watch their phones, only looking up when the referee describes the next shiny thing, then quickly losing interest, behaving as their characters do, as soulless husks devoid of humanity.  Pessimistic, I know.

 

The Elusive Shift is not elusive

After watching Matt Colville's videos, he recommends the book The Elusive Shift.  I have not read The Elusive Shift.  This is probably going to be an unfair assessment.

As far as I can tell, the "elusive shift" refers to how D&D started as a wargame and, somewhere along the line, became a role-playing game.

While it is true that, at its origin, D&D was not marketed as a "role-playing game," the practice of role-playing (some would call it character immersion) has been in place since Braunstein and Blackmoor. (This from a Questing Beast video on Braunstein)

However, if the book is primarily concerned with a terminological development, I would deem it to be useless. 

My argument is, then: There was no shift.

Or rather, not as such.

This is where my thesis from earlier comes into play.  The real shift was not one of being called a wargame to being called a role-playing game, nor of being a wargame into being a role-playing game, but rather the shift was that of the player base.

In response to the players, all wargame elements were removed from 3e, or rather simply not included in the first place. (No rules for dungeon crawling, mass warfare, building castles or running domains.)

However, this being what I find interesting, there has been a second shift.  The results of this shift is that the modern player base has turned the game into a story game. (See Critical Role.)

Conclusion

There are only three gaming cultures within TTRPGs:

1: Those who read the rules and follow the rules.

2: Those who read the rules and try to break them.

3: Those who do not read the rules.

 

Be seeing you.