IMHO, this is only partially true...I agree that data should not rule during the race but occasional glances at the data can give you vital information about how the race is unfolding relative to your performance limits. Combined with what your body is telling you it would give you an ideal of "how many matches that you have left to burn".

For example, I was racing the state RR championship (cat 4) and toward the end of the race i noticed that the avg. power was below my FT. This either means that everyone is tried or that everyone is holding back. So I took a chance lit it up in the remaining miles and got 1st! Of course the data just verified what I felt, that is, the race felt slow to me.

The moral of the story is that using this data in real-time provides a huge competitive advantage and that is why the pros do it.