I think that the point is that for most definitions of "civil timekeeping" you just do what Unix does and ignore the leap seconds altogether and simply live with the fact that once in a while one wall-clock second takes two SI seconds (or does not exist at all), probably by simply being completely oblivious to that fact.
Don't even get me started on UNIX time. On that I agree with the parent comment, whatever the time scale, you shouldn't fuck with it. Alas, UNIX is what it is..
You are asserting that without any justification. I see no benefits and lots of downsides in having leap seconds in civil time specifically.