This is helpful information. TBH, 15 projects out of 2968 defining or using a definition of an operator containing / is more than I would have predicted.
In the absence of the data here, if Swift did not support unparenthesized references to operators and there weren't other parsing issues requiring innovations such as the no-leading-space-or-tab rule, I would have been pretty sanguine about the bare /.../ syntax even if it meant requiring the banning of / in prefix operators, since I've always thought that to be a niche thing.
But, in the face of the empiric data, to me the amount of breakage itself is sufficient enough to call this syntax into question even independent of the other issues that were more what I fixated on.