People put serious effort into even IE compat for a while. AFAICT the beginning of the end came with trying to do battle with mobile browsers; you simply couldn

People put serious effort into even IE compat for a while. AFAICT the beginning of the end came with trying to do battle with mobile browsers; you simply couldn’t debug all the potential problems well enough. I remember burning a month on a regression that affected only iOS before Apple fixed it. Of course people were going to eventually pick an easy standards based target and tell everyone else to pray.