Actually, that's not really true. An ORM will almost always attempt to convert your object access to SQL. It's not always possible to make it work as well as a rewritten query. For instance, sometimes you need to use an EXISTS, or change a join order with a hint, or find a better way of reducing the driving table's rows to get better performance.
With an ORM, no matter how much tweaking you do, it is sometimes impossible to get the performance that a well written SQL query can achieve. And that's not because of bad code, or that the ORM is a bad choice.
BUT...those are problems that an ORM is not a good tool for. If someone is trying to use an ORM for that, that's the programmer's fault, not the tool's.
The same can be said of the goto statement, or any number of other things - used improperly, they screw up everything, but in some instances they are necessary and good.