> If trans people have such an obvious advantage why aren't they dominating every single category of every single strength-involving event?

Because there are fewer of them competing. Not every man is more athletic than every woman, but the most athletic men are more athletic than the most athletic women.

If me, as a man, tries competing in a women's weightlifting competition, I wouldnt do well, but I wouldn't do well in the male category either. But if you take competitive male athletes and have them compete against females, they will be incredibly competitive.