[graue]

The FSF quotes the new version with "and/or" in the blurb claiming problems with wording, but that may just be an editing mistake; maybe someone went through and corrected the quotation without realizing it resolved the concern.

Either way, though, the OpenBSD folks didn't change "and" to "and/or" in their template, which ranks high for a search for "ISC license". Someone could easily copy the older, problematic version. Given the MIT license works fine, why take even a small risk?