The subject of the blog post is not truly reflecting the fact that a series of (bad) decisions to release a breaking change on NYE could have side effects on many of the 1000s or 10,000s of users of ruamel.yaml that didn't pin the version in their Python projects.
I appreciate the time the author of ruamel.yaml detailing the reasoning for his changes, but again we see how much responsibility a single developer has for libraries that we take for granted and the lack of guardrails around those can cause unforeseen issues.
I still don't understand the logic to deploy this on the last day of the year. ¯\_(ツ)_/¯