It's one thing to belong to a fanbase. It's another to be part of a fandom. They're not the same thing.
Fanbases are broader, consisting of level-headed casual fans who, however avidly they like something, aren't fanatical and obnoxious about it.
The other component found within fanbases are fandoms. These are the cult-like hive mindsets that are fanatical and obsessive fangirls/boys over whatever they are into,.
They adopt annoying collectivist mannerisms that make them behave in a way their fandom demands by subtle peer pressure. So an member of the "Bro Army" will call you "bro" and be pretty miffed if you don't care for Pewdie Pie. A brony will insert My Little Pony stuff such as "every pony" into their communication, and not be too pleased if you dislike MLP. An otaku will often end questions with "ne?" and use a mix of English and Japanese and do anime smilies like ^_^ and XD . They never get tired of talking about anime, and will get upset if you don't like it. An anti-furby will comment on how furbies are Satan's spawn or gremlins that shouldn't be fed after midnight, how creepy they are, and make up furby horror stories, or furby-destruction videos.
Members of fandoms often give themselves titles such as "Bro" for a Pewdiepie fanboy or girl, "otaku" a member of the anime fandom, "brony" or "pegasister" from fandom for My Little Pony Aka MLP etc. A Pewdiepie fanboy calls himself and others "bro", Twilight fandom call themselves "Twi-hards", and proclaim themselves as being "Team Edward", "team Jacob" or Team whoever they have a crush on in the series.
When addressing another person, otaku may tack on these annoying honorifics so that someone named Kim gets called "Kim-san", "Kim-chan", "Kim-sama" etc.
These micromemes are irritating catchphrases, sayings and action mannerisms, each different set specific to their various fandoms, but aren't something people outside of fandoms tend to do. But it's all so repetitive among fangirls/boys wherever they go on the net. It's as if they've all lost their sense of individuality and their own style and prefer to be part of some fandom and its echo-chamber.
But it's all there within anti-fandom, which is actually a fandom and not a legitimate opposition to fandoms or anything else for that matter. It is a specific type of troll subculture that ends up being the worst of everything they claim to oppose, and just your average troll in a general discussion.
Anti-fandom is similar to the cult of otakuism that consists of smaller fandoms of anime. The difference is that otaku are into anime. anti-fandom is into hating other fandoms "for the lulz". Antis aren't interested in true opposition to fandoms and being supportive toward people who genuinely dislike what fandoms are doing. Antis are only interested in trolling and getting a rise out of whatever fandoms they think it's cool to hate.
Like otaku, anti-fandom doesn't mean disliking all fandoms, not even for the right reasons.
For example, someone can be anti-brony, yet be a Pewdiepie fanboy/girl, one of his "bro army" or an otaku for certain anime.
Anti-fandom is no better than any other fandom. It's actually worse. Anti-fandom consists of brats and trolls who are just as bad and fanatical. Not only does anti-fandom contain all the hate seen within other fandoms, it also contains various annoying mannerisms from other fandoms. So within anti-fandom, there is a mishmash of "Bro!" (Pewdiepie) "every pony" (My Little Pony) "Ne? Baka! Desu desu desu!" (anime fandom). and on.
Anti-fandom is to fandom what anti-chains are to chain letters - part of the problem!
And that's not the worst.
People who are level-headed fans, part of any fanbase and not the fandoms or troll subculture, don't engage in this irritating, embarrassing and even disgusting behaviour.
Most Annoying Things About Fan-brats