frankly speaking, button ability is badly interpreted in the game both current and previous version of it. It absolutely does not make any sense that firing lots of bullets could stun and ensnare the tank. And the current version that only stop the vehicle from moving when historically its the opposite.
Excerpt from
Observer's report on the destruction of two German Tiger tanks by British anti-tank guns in North Africa, from Tactical and Technical Trends, July 29, 1943.
"One element of this action contains an important lesson that should be brought to the attention of all AT elements and particularly tank destroyer units.
(a) "The British gunners did not open until the enemy tank was well within effective range.
(b) "In addition to opening fire with the primary weapon -- the 57-mm -- the AT unit also opened with intense light machine-gun fire which forced the tank to button up and in effect blinded him. His vision apparently became confused and he was actually traversing his gun away from the AT guns when he was knocked out for good.
(c) "Once they opened fire, the British gunners really poured it on and knocked out one more heavy tank and six PzKw 3s. Also, for good measure, one armored car."
The conclusions to be drawn from this action, according to the British officer quoted, are:
(a) "The unobstructed vision of the gunner in a tank destroyer gives him a very real advantage over his opponent squinting through the periscope or narrow vision slits of a tank.
(b) "The tank destroyer unit must force the enemy tank to 'button up' by intense fire from every weapon he has, including machine-guns, tommy guns, and rifles."
The size and weight of a tank such as the PzKw 6 present many problems. It has been indicated from unofficial enemy sources that extensive reconnaissance of terrain, bridges, etc., was necessary before operations with this tank could be undertaken. Bridges have to be reinforced in many cases, and soil conditions must be good for its effective operation. It can therefore be assumed that its field of operation is limited.
TLDR: the Brits figure out that LMG fire would forcefully "button up" tank crews by blinding their vision.