Imho, as long as there's fanserivicey chicks with the stereotypical personality of an anime( like Asuka Kazama), that will be cancer to the haters. How this connects to ryona freaks is they love to fantasize their "happy time" with their lady of choice.
The minute Chun-Li was introduced or whatever female character came first, I'm biased to believe the "pandora box to kinks" has been opened. If anything, place blame on the ladies looking too fanservicey for us horny guys.
Look at pokemon fashion then and now for instance.
Before
After
These two trainers are just some typical examples of fanservice growing at an alarming rate for FGs. Yes they're terrible examples as they're not FG characters, but the fashion trends of japan really shows. A simple plain jane to a more suggestive outfit. In other words, stereotypical anime fanservice fashion is to blame.
Blame the lolis, tsundere tomboys, Yanderes, big boobed serious chicks, the rich ojou-sama, sugary yet clumsy kawaii desu girls, the quiet kuuderes, elegant and ladylike yet scary when angered chicks, sadistic flirtatious lady and whatever else stereotypes I forgot. All catered and recycled to fit every guy's fapping needs. Ryona as I mentioned earlier is just a personal closet kink. The real cancer is certain Japanese trends picked up. If anything, anime + stereotypical fanservice lady of choice=cancer. As much as I love Japanese stuff, there are things that don't even sit well with me.
Those peeps into lolis.......yup I'm definitely staying away from those weeaboos who love Amy Sorel in SCIV lol. So there you have it, anime + stereotypical fanservice lady of choice = cancer. Why? I can't stop fapping to tsundere-ish Asuka Kazama for instance lol. That's enough to tell you that it's contagious.