That is, not to think of symbols as having a mysterious "meaning" apart from their formal definitions.

Pure formalism is useful for developing new math, but math cannot be applied to real problems without the assignment of meaning to the variables and equations. Most people are more interested in using math than in what amounts to intellectual play, as enjoyable and potentially useful as that can be. Note that I tend to be more of a formalist myself, which is why I mentioned in an old comment on HN that I tend to learn math concepts fairly easily, but have trouble applying it.