Airflow direction in rack-mount cases

Hi, I'm aware of some standards that dictate airflow direction in rack
mount cases (e.g. ETSI 300 119 and NEBS), and it's usually front to back,
bottom to top, or (least preferred) left to right.

But recently I noticed some equipment from Brocade in a 1U case that drew
air in at the back, and blew it out the front. This is actually mentioned
in the data***, so it was not an assembly error (with the fans in the
wrong way around).

Why would designers go against the standards and do this? Could there be
some benefit to the equipment?

Curious,
Allan
.