From my perspective, writing a text clarification PR (such as Attempt to clarify environment marker evaluation by ncoghlan · Pull Request #1988 · pypa/packaging.python.org · GitHub) and writing a full PEP (with format, editing, core dev sponsor, submission, pre-merge iterations, approval, separate DPO thread, and then finally still the packaging.python.org PR, which may require clarifications different than the PEP) are a massive difference in burden, especially if the alternative is making an (undocumented) decision at tool level.