So, I figured I would explain why I tend to avoid all sorts of fandoms in the first place.

In my early years of... Well, browsing the internet, I have never paid much attention to popular fandoms, neither joining nor avoiding them directly.
Hell, I only ever came to know about what Homestuck or Hetalia was just nearly 2 years ago, maybe even less.
I was that much disconnected from popular fandoms.

The first interaction I remember having with a fandom was the Sonic the Hedgehog one.
I liked Sonic, back then. Still do, actually. I might not play the games every so often, as other games have caught my attention (namely Salt and Sanctuary and Darkest Dungeon), but at times, I do like to play the old Sonic games and have a nice, short nostalgia trip.

But back on track, Sonic's fandom.
It was baaaaaaad.

All the fanfics, all the poorly-done art, all the terrible recolor OCs... Things like that can make you drop a fandom faster than you could say "SEGA".

And so I did. I distanced myself from the fandom and anything to do with it. I even stopped playing Sonic thanks to that, as dumb of a decision as it might sound.
I began to do the same with most popular fandoms, to the point I held the word "fandom" as something repulsive and... Blasphemous, would you say?

Fast forward a few years, and I stumble upon a little game called "Undertale".
I watched some gameplay videos... And I got hooked on it.
I bought it legally from Steam, and played it. Now, I won't say the game is perfect, or that it's the best game ever made, because that's simply not true. I won't even say the game is great, one of the best of its time, or stuff like that. In other words, I will not defend Undertale, neither the game nor the fandom, when someone comes to me and says either of them is bad.
All I know... Is that I personally had a great time with the game.

I loved the music, the atmosphere, the comedy, the gameplay (sort of), the characters... Especially the characters.
I loved Asgore's character the most, followed close by Undyne and Papyrus. And Flowey? I loved Flowey as a villain. His dialogue, his expressions, his goddamn final boss battle, and the theme song accompanying it... It was excellent.
So in a few days, I finished Undertale, pacifist route and all. It was a nice ending for a game.

So I uninstalled it from my computer, as I was simply done with it, in a good note.

...Then I came to know of the fandom.

I came to know about the horrible fanfics.
I came to know about the horrible art.
I came to know about the horrible, HORRIBLE OCs.

It was the Sonic fandom all over again.

But this one... This one was worse.
Along came the horrible ships, destroying any and all good character dynamics for the sake of "romance". Along came the rabid, idiotic fans, defending Undertale like they would someone close to them, yet ironically solidifying the bad reputation they were given. Content creators receiving hate comments, insults, even death threats simply because they were not doing what the fandom wanted them to do, like playing the game in a specific, strict way, or not taking any time to rest after making an Undertale-related animation, because they just wanted the next one sooner.

And thus, I dropped it. Just as I did with the Sonic one. Not without giving some of those rabid, idiotic fans I had the pleasure to meet a piece of my mind.

All other fandoms followed suit. FNAF, Steven Universe, Bendy and the Ink Machine, most anime fandoms, the Creepypasta fandom...
I used to like reading Creepypastas. I always had a thing for horror stories, whether long or short, and most
Creepypastas were a nice read.
But alas, along came the fandom, and completely ruined the concept of a Creepypasta, reducing it to nothing but shipping material. Horrifying creatures and mysterious entities, out for blood or other malicious intent, now they're just shipping fodder for the fangirls, ruining their character and purpose. You know, to instill fear.

All respect I had for most Creepypastas was gone. I used to love Slenderman's concept and design. It just set the right mood. Ben Drowned? I never really held game Creepypastas that high, but that one was sure something. Jeff the Killer? Nah, that one fucking sucked anyway.

And the stigma I held for fandoms just became stronger.
But that is mostly just the fandoms, a the media they follow is mostly alright in my book, often being games and shows I personally enjoyed.

So... Yeah. That is why I avoid most fandoms like the Black Plague.