That's bullshit you should change yourself to get a relationship. The only people who say that are people who want to make excuses for why they're single.
I'm just pointing out the irony in what people have been saying and what the reality is. People have preferences in who they want as a boyfriend/girlfriend, they have every right to have that. But if person A is not getting the person B of their preference, or if their relationship with them doesn't work out, and it becomes a repeated occurrence, then the issue may lie with person A than their ideal person B, so they need to do something to change that, in other words, change themselves.