Links to external resources may be perceived as an endorsement by python. They also can change over time, and may not say what they did when added to the documentation (and may actually be offensive or dangerous). If linked content becomes problematic changes to the docs in active releases will be delayed by release cycles and won’t update any local caches, etc. There may not be a quick fix to dissociate python from whatever that content has become.
I do think there is value in this type of link because including the entire blog post in the docs is also inappropriate…it is too much tangential detail for what should be concise documentation. A link to a python (PSF) controlled site such as the wiki that another thread is discussing the fate of seems more appropriate ( [Feedback requested!] What’s next for the Python and PSF Wiki? - #12 by Mariatta ) since the additional detail can be linked to but control over that content would be retained.