IF this game was designed to be a campfest behind bunkers, mortar pits, pillboxes, heavy AT gun emplacements etc., ofc then ISU and ST would fill their realistic role to destroy those things.... But this game isn't like that
For example the ISU gets rid of houses and everything that can be built on the field by axis, they can't fill their "real" role as Assault Guns in a game which isn't made to be realistic.
Want a game in which a Sturmtiger shoots 100+ metres and kills 3 tanks that are 5 metres away from each other because it's realistic? Go play Men of War. Want a game that's not realistic and is more based on balance and smoother gameplay? Then CoH2 is for you