I was under the impression that that website is outdated. The ISC used to just say "and distribute", which is similar to older versions of the Pine license, and had problems. However, the new language is more similar to the MIT license ("and/or ..."), but the FSF does not have an issue with the MIT license.
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?
https://en.wikipedia.org/wiki/ISC_license https://www.washington.edu/pine/faq/legal.html https://www.gnu.org/licenses/license-list.html#X11License