To be fair, your credit score can be affected by someone else's actions if the credit tracking agencies screw up and think you're the same person... This is hopefully harder to happen now, but my mother and her brother had the same initials in a different order and their SSNs were different by only one number and somehow the credit bureaus messed up and it was a headache getting that untangled.

That said... Yeah, that's absolutely not how it's supposed to work and if it happens it's because someone somewhere screwed up.

Now that it's all computerized, the odds of that happening should be pretty slim, but things do still go through a human's hands at some points of the process so it's still not impossible.