You don't symlink everything in /usr/bin to /bin, just "all regular files that have traditionally been in /bin" (per the article).
python3 has not traditionally been in /bin, so /bin/python3 would not be linked.
You don't symlink everything in /usr/bin to /bin, just "all regular files that have traditionally been in /bin" (per the article).
python3 has not traditionally been in /bin, so /bin/python3 would not be linked.