4 reasons In order of importance.
1. It is not plug and play like expected. It needs a hole drilled in the air intake near the turbo for their grommet and adapter to enter.
2. The fuel injectors are both port and direct injection. So gunk theoretically will not build up on the valve.
3. Don't want any extra mod that would cause dealer to think twice about the extended warranty. (I know burden of proof is on them)
4. When I called the Ford technicians, at least two of them have never heard of a catch can, tells me it is not something widely used.