If fight mechanics were more random instead of scripted, I would probably agree with you OP. But things like positionals still keeps fights interesting after you've learned it. Keeping up a optimal rotation while dodging mechanics and still landing your positional bonuses is quite challenging, so you're basically asking for an element of difficulty to be taken away. It's like me asking for no unavoidable AoE as a healer, or for no tank busters as a tank. These are elements for each role that the player controlling them can't do anything about; they can only handle them in the best way possible. Mechanics are meant to disrupt your flow, and punish you if you don't follow. If overlapping mechanics make it difficult to land positionals, then welcome to content that challenges you.