Hi Anna - from an IB friend who's applying this year?
No, its not true - well, its a mere correction on semantics. Colleges regard predicted marks with AS MUCH credence as the actual marks. The same - not more, but not less.
Just as Sydney Uni shortlists Merit Scholarships based on predicted ATARs (and essays), overseas colleges make admissions decisions based on predicted results and grades (IB, even reports) and the essays in the applications package.
Hope that helped clarify!
Wendy xx.