It is possible that the WT could be tiered like it was in Awakening based on weapon rank and everyone here has low weapon ranks meaning very little effect on hit rates. Also possible that they've lowered the doubling threshold. I mean Edgelord did have 0 AS (and 0 avoid, yeesh).
Actually the more I look at it the more I think you're right in that it has been removed (or maybe turned off ala RD Hard mode). Edelgard goes from 71 Hit to 67 Hit. Mercedes probably has 2 Luck, assuming 1 Luck still = 1 Dodge, and if we also assume 1 Luck = 1 Avoid and we know Mercedes has higher AS than Edelgard b/c she doubles, we might assume 1 AS leading to 4 total Avoid?
This also presupposes something weird like Biorhythm doesn't exist or one of them doesn't have a skill that outright cancels the triangle, or the formation is doing...something.