[pilif]

The commit is written by postgres developers for postgres developers. I would say that 90% of the intended audience of that commit message doesn't need an explanation what table partitioning does.

For them this would be needless clutter that's not at all relevant to the commit.

Once we're reaching the 10.0 release, human-friendly release notes, additional manual chapters and sample code will be written for the users to understand (in-fact, the commit linked by this submission already contains quite a bit of additional documentation to be added to the manual).