As Andy says, some people still like to fit an Mmax, Kiss, Posh etc delimiter. I am guessing that some (a small number these days) still actually believe that there's something special in there, and other just don't like to get in there and start cutting and soldering. I can understand that.

Fact is that they do nothing other than a simple wire splice, and in my opinion they just clutter up the bike with unnecessary boxes. Splicing yourself allows you to keep all the wiring tidy and looking standard.

Only if you've got an HRC box in line should it be on show. Just so that you can brag down the chip shop.