Wouldn't this sort of shenanigans be a problem with Ripple as well? And I have to profess ignorance about how Ripple works, but I'm pretty sure it's just as centralized as IOTA is.
It is a very different case that needs to be handled on its own. Evidently, Ripple does not claim to be a cryptocurrency such as Bitcoin AFAIK (they are something else entirely) - despite their frequent attacks and public lies by their CEO (public as in in interviews and similar). They will get their chance in the spotlight as soon as there is more time.