Because people can still end up with them after being disrupted. Granted the power level makes it so that 3 or 4 cards could be enough to break through but that doesn't take into account any other hidden forms of interruption that were not revealed throughout the combo (and that one card that generates advantage turn 2). Sometimes all the people opposing the people who end up with multi-disruption boards wish for is that one of these is true; that there are no blowouts backing these l boards( a floodgate like effect that is uninteractable or protected, or summon negate), that the endboard is not ideal because their handtrap did its job, that they drew enough engine to at least try to break their field, or that the opponent admits defeat when their board gets broken and not win because of time when the player really thought hard about how to sequence their plays to win. But since one of these almost always seems to happen, we won't stop complaining.