An extension & refinement of the MOP theory.
The function of any given community is social noise reduction: a community allows groups of people with certain sets of attributes to access each other with fewer “misses” — i.e., without accidentally interacting with a person lacking any of these attributes. (Whether or not this is a good thing depends pretty heavily on the circumstances; however, ultimately, a country club, a Bilderberg conference, a birdwatching forum, and a hackerspace all have in common this basic definition.) Gatekeeping is therefore a huge part of the function of the community.
In a sense, the gatekeeping rules of any community define that community. After all, gatekeeping rules ideally act as a test to ensure that members approximate the ideal community member, but functionally, gatekeeping rules specify who gets into the community and therefore what the range of attributes are of community members. Gatekeeping rules are rarely explicit, and many are inherently implicit: after all, community norms, tolerance for particular community members, and desire to be part of the community all have major gatekeeping ramifications despite never being written or systematically enforced.
Communities are not the result of people coming together so much as they are the result of people seeking a temporary separation by some arbitrary category. They happen naturally, as people congregate toward other people who can fulfill needs and desires. When a community becomes diluted such that different sub-groups within it have different needs, it fractures into multiple communities, whether or not anybody recognizes or points this out for any particular group. Community fracture is always present and fractal to some degree: cliques appear within any community among people who get along better together, and this is part of the community fracture gradient and caused by the same impulse toward sorting. However, all of these organizations are temporary and desire-driven: someone who ceases to be interested in hot rods has left the hot rod community, and communities don’t organize along racial lines in the absence of racial tension. The rich and powerful form cliques among themselves because they share attributes that are only accessible to them (nasty gossip about foreign dignitaries isn’t available to people who aren’t presidents; discussion about how to prevent your kids from murdering you for your inheritance isn’t useful for people who have no estate), and pooling power is a side effect rather than a goal.
Prior to complete fracture, a cultural change within a community changes the community’s ideals. When somebody leaves a community and calls it “dead” — it’s not dead, but it no longer serves the purpose that person needed it for. Communities are tools for solving particular social/interpersonal problems (usually, a desire to communicate about a particular subject), and when community norms change, it’s as though someone’s screwdriver has been replaced with a hammer.
The MOP theory explains a very specific special case of this phenomenon — one that happens pretty frequently, particularly in “geek” circles. Specifically, it explains what happens when an affinity group organized around a particular subject becomes subverted for the sake of commercial interests. (When we talk about this in terms of Punk, or Star Wars, or comic books, we’re really talking about a set of established commercial interests that had already taken over partial control of a social group being subverted by another, larger and more powerful set of commercial interests with different norms.) Whether or not this is a good thing basically comes down to which norms align more closely with the ones you value. While typically the group that takes over has values closer to the notional “mainstream”, it’s not as though communities haven’t been taken over by commercial interests that are even more fringe — as with Palmer-Luckey-funded alt-right trolls infiltrating 4chan. That said, the typical pattern is as mentioned in the MOP theory: a community with a focus on detail and quality has its gatekeeping process subverted by a second group whose focus is on commerce, in such a way that an influx of less-dedicated members become involved; the average dedication level of the group plummets while the most dedicated group members leave the community to form their own. Without the most dedicated members, the infrastructure involved in gatekeeping and in keeping conversations going disappears, leading to most of the casual members also leaving, but enough money has been extracted from the group by commerce-centric outsiders to make this tactic a success.
When a community that has been infiltrated becomes self-sustaining (usually because the new gatekeeping mechanism is sufficiently exclusive that most members still find something valuable in each other’s company), it’s essentially a new community with new norms: obviously most of the old guard will find this new community less to their liking than the old one, because the old community was based more closely on their own desires and values. It also becomes vulnerable to being infiltrated, split, or subverted by some other commerce-centric group. Whenever a commerce-centric group infiltrates a detail-centric group, the group norms become more lax, because commerce works best at scale and details work best with strong gatekeeping.
While toxic community norms (as mentioned on the Status 451 piece) can become part of gatekeeping, they are rarely truly valuable as such. Communities with toxic norms can become stable so long as they consist primarily of people who can’t easily split off. Having been a long-time member of several autism-related internet communities, I can verify that schism doesn’t take a huge amount of emotional intelligence or social capital; more typically, toxic norms dominate in groups where confidence in one’s ability to split off is low & desire to avoid a toxic community is low — in other words, toxic communities are a result of learned helplesness, not a calculated tactic.