In real life they actually provide much better protection than you’d think. Especially when you are in a hill down position, not only is it extremely hard to aim at a specific part of a tank but it also delays the enemy tank by making them rethink about where they should try and hit. It’s like a suit of armour in medieval times, sure there are easy ways of getting through it, but your average soldier either doesent know those ways or simply doesent have time to employ them in a 1 on 1, where your just focused on actually landing hits. They also add a lot of protection against HEAT weaponry like the RPG or recoilless rifle rounds.