I would question this. I mean, you might think that once your Myspace/LinkedIn account details are leaked, it’s only of interest to people after bank account logins, say. I.e. it’s only of interest for high value logins.
But once account details are leaked in bulk pretty much anyone can download them and run through them, looking for matches with any service including ROTMG. The sheer number, with some leaks being in the hundreds of millions, makes it worth doing.