Proposal for Acceptable:
Updating code in old answers following software updates (e.g., a new package version)
Provided that the original code is preserved, to facilitate users with older versions and to show the effort of the original answerer.
See also Updating an old answer when my knowledge improves, or a package is updated.
I think I could add prof. van Duck's tutorials.
Section 3 Asking effective questions on TeX.SE of his first article in TUGBoat 38:3, 2017 explains how to build an MWE.
Section 3 How to format a post in TeX.SE of his third article in TUGBoat 39:3, 2018 explains how to format your question.