Universal Line Replacement Kit (80020001)

I am replacing the Spectra lines in my Outback SUV and ordered the Hobie Universal Line Replacement Kit (80020001). I received the kit and I like the internal sliding O-ring concept, but what I do not understand is that the Spectra line that comes pre-installed in the tubes/O-ring is not long enough to be useful without making a Spectra to Spectra splice within the kayak hull. The kit does come with a decent amount of additional Spectra line, but even as the included instructions say it would be difficult to get the Spectra into the tube and into the internal O-ring and suggests that it should be replaced as an assembly.
I guess my question would be “why is the pre-installed (into the tube/O-ring) Spectra line so short?”.