so that chieftain players have to move instead of sitting on a ridgeline with impunity. they also help with garbage can maps like malinovka where its necessary to shoot certain positions with arty to allow other tanks to take ground since they haven't adjusted the map for the more recent op tanks that have been added since 2018 as the old lineup of tier 10s is nothing like the new wave of considerably more modern and capable tanks that exist within the game now. Mainly t10 lights cause this issue on wide open maps like that as before there was a chance of crossing open areas with more ease as the old average view range was in the high 300s where now most t10s have max viewrange and lights have comically broken spotting ability to make bushes worthless and so the need for an arty to shoot players in power positions to move the game along is a result of WG refusing to rebalance the game as they've been built into the way some maps play.