Champions have ended up being 'Left in the Dust', or at least turned into average champions after a week went by of blind buys and first time people showing easily influenced level 3 Summoners that the champion is bad, because people decided to play without studying up on the champ. They just transferred another build it their place because they think just being AD or AP will determine a build.
(These champions are only recent champions that have been lowered in stature. I find some people on the wiki decide to show off their knowledge very extravagantly, which makes my blog a bad place to be. Please be wary that you're speaking to a very great player among peers, but still has a lot to learn.)
Take a look at Jinx. She was the much anticipated Crazy Girl from Piltover that ADCs were waiting for. They instantly bought her and ended up placing a horrible build for her and ended up sucking, which in turn, made the champion seem horrible to their peers, and then, made her not bought as much, which would give her the classification of, 'one of those champs'.
Yasuo was like this too. No one decided to figure out that Statikk Shiv is OP when bought with him and would increase your farm, which increases gold income and XP, which increased the amount you would get fed, due to getting your build faster and killing more champions because of your higher damage. People also decided that Yasuo was like Lee Sin and was good anywhere you put him, when his primary role was best as mid instead of ADC, where his farm wasn't able to be collected as fast, or top, where he would face tanks he couldn't get down easily enough, or jungle, where he wouldn't get enough farm and would end up not getting items fast enough. All of these flaws in the 'Yasuo Experience' as I like to call it, made him seem horrible and nobody recommended him.
What I'm trying to say here is that you need to study up on new champions you buy, or find someone you play with that you trust to give great information to you, like I do, before you go in with your first time to play it. That, and/or you can try the champion when they're free, which I recommend, before you buy them to see if they fit your style of playing and you feel comfortable playing them. I say and/or because doing the studying then playing the champion for free is better than buying it right away.
Thank you for your time to read this blog, and I hope you get my point of view on this topic.