That wasn't my point either. My point is that if chess allowed white takebacks ( as in tennis ), the white advantage would skyrocket to 70%+. The analogy was pointless because it wasn't comparing likes with likes.

> but that the advantage for moving first in chess is much smaller than is already accepted in other sports.

Yes. But in most sports, you get equal or close to equal chances to 'move first'. In tennis, you alternate serves with each game. In football, you take turns playing offense. In chess, it's not necessarily like that. Some tournaments you get to play the same opponent with black and with white in equal amounts. But in many tournaments, that's not the case.

So in tennis, you are pretty much guaranteed an equal game since both sides get to serve. But in chess, even though the first move advantage is less, it's still more significant than in tennis many tournaments don't have equal games of white and black.