Thats why you compare how dominant they were at their time to the players of their time since you level the playing field by making sure you arent comparing people who have the modern sports science they do today to people who don't.
Here is the disagreement, you're telling me they can't be compared because they had different trainings and I'm telling you they can't be compared because they didn't play the same people.
Let me put it differently, by your logic, Vision Strikers is the best team of all time because they were most dominant at their time. Regardless of them only playing Koreans and how much the game evolved since then