Ok sure. In that case, I'll point out that being "a common practice going back hundreds of years" should lead you to question something, not accept it.

It reminds me of the time I recommended (to the Unix team at a major financial institution) that they use ssh rather than telnet, and being rebuffed with "that's the way we've always done it".

In this case, since you want to be specific, the practice of defaulting to "he" correlates with hundreds of years of treating women as chattels, with economic consequences and imbalances that persist today, and continue to be reinforced through structural, unconscious, and explicit biases, and that we'd all be better off without.

The notion that language should reflect thought is as old as Plato.