I don't think it is such a stupid question.
Overtaking (ie. being on the wrong side of the road) is probably the most dangerous manouvre.
Therefore you need to do it as quickly as possible. If you are behind a vehicle doing 20mph in a 30, and the road is clear, you want to overtake and might exceed the limit briefly to get past asap.
It's not legal but does make sense - just don't do it if you see those white dashes down the edge of the pavement!!