It is likely that Swift's choice (deviating from many of its peers) to emphasize its dynamic array through sugar, has led to a negative impact on the culture of writing performant Swift code, with the nicely sugared dynamic arrays (and array value literals) being over-favored.

This is likely a hypothetical concern rather than a practical one since of is very rare as a variable name. The previous proposal's use of x involved a variable name that was more common.