I would say i agree with Grave here, but Grave's stock is tanking right now in the community with his recent bans in Xcom and Staty's stream, so I wouldnt want to attach myself to a sinking ship. (i'm fully jk, making fun of the absurdity of this community)
v-snejok, pak abuse is continuously resetting the pak to avoid the reload time. As a result the pak fires much more rapidly than intended.
It's clearly an exploit of a bug in the game mechanics. Fundamentally no different than a previous exploit (since patched) which allowed cloaking bonuses to stack. Players exploiting this earlier bug would cloak and uncloak a pak a dozen times in quick succession such that the pak could then single shot kill a full health triple vet Pershing tank. Not sure why anyone would be ok with either exploit being used.