There has to be a balance. I grew up the opposite way: believing that everything bad that happened to me, whether it was genuinely my fault, or someone else's or just the system or bad luck or whatnot, was entirely my fault. If someone didn't like me, I had to change my behavior to change their mind. If I didn't win at something, it was because I was born to be a failure and because I didn't try hard enough.
It gets really hard to shoulder all of that self blame, and it can be just as detrimental. Though coming to rely on blaming others for your shortcomings is also self-destructive, I get why people might become predisposed to it. It's just easier. It's also healthier sometimes, because sometimes the system is unfair and you don't have control over every little thing that happens to you, so you have to learn to let go of many of the things you can't control so you can focus better on the things you can do.