So would you say it's fair game to blame "migrants" for crimes? After all, you can't steal something if you're not in a country, so letting someone into a country strictly increases the crime rate. Even if migrants commit crimes at a lower rate than the local population, unless it's exactly zero, it'll still increase the crime rate.
edit: downvoters, I'm not actually endorsing blaming migrants. It's only used as an example.
edit: downvoters, I'm not actually endorsing blaming migrants. It's only used as an example.