I don't think it would mangle your data directly, but it could lead to incorrect results since there is a degree of mystery from query to query. You should definitely base a conclusion on their words and not mine.
The reason most people don't complain about this is that it's a far from common issue to totally miswrite your SQL statements so badly that you wind up mixing up columns. And when you do, it's usually detected pretty fast.
Maybe you are thinking about foreign key constraints, which for backwards compatibility are off by default, unless you use a compile-time option to make then on by default.