You can generalise: men and women do bring different skills to the table. Where generalising falls down is in applying preconceptions, categorising a person as such without learning what they as an individual can do.
Generally, I believe it is true that women are of the same skill as men, but that differences in they way they operate exist - probably largely borne of our genetics.
Those who dismiss outright any notion that sexes differ are really putting themselves up to be shot down - not only does science show differences, but being PC is quite different from being a militant PC-enforcer.
In my current field, I have come across some women who are more pre-disposed to getting the task done - this translates occassionally to neglecting the big picture and missing key changes even if the detail has been completed correctly and as asked. I find that men are more pre-disposed to letting their mind wander on their task, allowing the big picture transformational items to be picked up, but missing some details.
Knowing how people operate is key to efficency in performing the task - DvB's suggestion that there might be a difference is a valid question.
As to why he asked the question - he may well indeed recognised that he believes women should be in the kitchen - many women do as well - this is largely irrelevant so long as you understand your own prejudices and work around them.
I challenge anyone to say that they have no prejudices whatsoever - I know you are lying if you say you do not!