I personally think that they are like WT auf E100 just broken and as long as they continue to have the ability to one shoot top tier tanks they will be, no matter how much they nerf their reverse speed, dispersion and other stuff. When people mention this there are usually comments about how they rarely pen tanks, but arty also rarely penned tanks and it was deemed toxic, so why don't these tanks get the same amount of hate?
Furthermore these vehicles much like arty are probably most frustrating things to play in this game since they have super long reload and miss most of the shots they take even when fully aimed unless you are in spitting distance of enemy tanks. They are also most RNG dependant vehicles in the game, a game where you hit 5 shots could've been 8k game if you were lucky or 3k game if you weren't so lucky. In 90% of scenarios these vehicles don't out play others, they just get lucky, like playing black jack and getting 21.
These vehicles are bad for the game and actively make everyone miserable. The whole shtick of these vehicles is to ruin someone's game and go up in flames moments after getting spotted, thus I think they are bigger cancer than other vehicles in the game.