Defining core skateboarding used to be simple. As much as skaters hate being an “organized sport” there was very much a centralized hierarchy within skateboarding similar to that of the NFL. With the NFL there is a typical path to understanding, pursuing, and becoming a professional or being involved somehow in the industry of professional football.
Play as a kid -> train and compete in high school -> play division 1 college football -> get drafted
There are anomalies, drafted out of high school, etc., but this is generally the standard process to becoming a professional football player
The process in skateboarding (pre Instagram/pre olympics):
Play as a kid -> start to develop skills, maybe film a sponsor-me tape -> shop flow, rep flow, company flow -> AM -> PRO
It is important here to define Pro as “engaged in a specified activity as one's main paid occupation rather than as a pastime.” Not just having your name on a board, but having your name on a board, shoe, or sponsor of any kind of a company that makes enough money to support the team riders as a full-time employee. There were and are only a handful of companies that do this. That is where the centralization comes from, and they were all generally located in California.
Being a part of “Core skateboarding” should be defined as being a part of and having a general understanding of and interest in this “process” to becoming a professional. Every kid has a dream of becoming a pro so they study and learn (watch skate videos, go to demos, go to the skatepark) how to do that.
In the 2000’s, if you went to a skatepark, everyone generally understood “process”. You didn’t have to be on track to even becoming sponsored, but you understood the “process” and your position within the heirarchy. Talent + effort was recognized and filtered through the best skateboarders to the same centralized destination.
With ongoing development of the internet and social media, globalization has decentralized skateboarding, which has revealed several issues with the “process”, and provided alternative routes to getting a paycheck through skateboarding (revive, braille, youtube, etc.). Now “core” is more difficult to define, but I would argue should be defined similarly.
Although always changing, there is a “process”. Deal with it and move on. If you want to choose an alternative path, feel free. But to act as if you aren’t aware that you have chosen an alternative path is where the tomfoolery begins.