Fandoms are detrimental because they can foster toxicity around a given figure/franchise
When it comes to fandom culture, it is easy for participants to become carried away. That because fandoms and their participants have intense feelings towards the object or person of their affections, this propagates equally intensive negative feedback where there is some to give. Should one observe fans of modern music artists, this trend is something that can easily be spotted. For instance, a Canadian writer named Wanna Thompson offered some mild criticism to American-Trinidadian rapper Nicki Minaj. Fans of Nicki Minaj outpoured over this criticism, not only directing all kinds of crude and graphic language at Thompson but also singling out and attacking her 4-year-old daughter over Twitter.  Even though Thompson's critiques were not overtly damaging to Nicki Minaj and her career, this prompted the rapper's fans to come to her defense. The fandom's response to Wanna Thompson was already somewhat uncalled for, but what made the fandom's approach undoubtedly toxic was when they began to go after Thompson's daughter, someone that had no bearing on the debate at hand. This behavior is not limited to the music industry and is observable in the movie industry as well. When Star Wars: The Last Jedi was released in theaters, fans of the franchise made clear their dissatisfaction with the film and what it tried to do. They harassed the cast and crew of the movie online, most notably the actress playing Rose Tico, Kelly Marie Tran, who left social media because of all the vitriol she faced for playing her character.  Since Star Wars fans felt betrayed by the people who had a hand in the creation of The Last Jedi, they saw fit to lash out against them for what they perceived as a trespass. The fans' response is without a doubt attributed to their love of the franchise, much like what took place between Thompson and Nicki Minaj. In essence, a fan's love for their chosen figure or franchise can easily find itself weaponized as a defense mechanism against those who they perceive as problematic elements.
Fandoms might appear to outsiders as problematic, but to others, they are much more than the anger and frustration they seem to spew. Not everyone who participates in fandom culture has to have violent tendencies or consistently pick fights with other people. Being part of a fandom more often than not brings people together than it does create rifts. For some, it can improve communication between two parties, such as that of a mother/daughter relationship. Anthropologist Susan Kresnicka was able to forge and reinforce a bond with her daughter through their shared appreciation of the CW's Supernatural where before they were having difficulties.  Having this bond between the two only served to strengthen their relationship, as it gave them a secondary way to communicate in a way both parties understood. As this instance demonstrates, joining a fandom works more towards building bridges as opposed to burning them.