Well, that is sometimes the case...not sure 'stupid' is the right word tho.It's a point of humour for some and the chicken gets dismissed as too stupid to find it's way out.
Like everything else it depends on the breed. Some birds will kill themselves through the wire. I’ve seen both birds start it. It’s territorial behavior.If it was just bravado then looking at it from a human perspective, the moment both/all parties were able (free) then one would expect the stronger hen or rooster to beat the crap out of the weaker. Ime this isn't what happens.
I have a couple of maternity/isolation units which have small runs attached. Each run has a door as an entrance. A chicken can be in the run but while the door is open these fence fights don't occur. Shut the door and it's a different story.
Many chicken keepers will have seen a chicken in an enclosed run wandering back and forth along a fence when the run door is open, seemingly looking for a way out. It's a point of humour for some and the chicken gets dismissed as too stupid to find it's way out.
The two views are not compatible. If a chicken knows it's safe to taunt another chicken because the door is closed and he/she can't be got at then the idea that they are too stupid to find there way out when the door is open doesn't really make sense.
Usually from what I've seen it is not the enclosed chicken that starts the fights; it's the chicken on the outside of the fence.