Nylon stretches. Polyester(dacron) would be a better choice.
The issue is spacing more than tension. Both count but spacing is harder to adjust. ;-)
The ideal puts a 30 deg rope angle at a height you can reach with your butt off the ground. If we could always do that the ridge line would not be an issue.
If you do not achieve the ideal spacing the ridge line can be tight on any hammock. That is why it is there. It establishes a hang length for the hammock that should simulate those conditions. Comfort can vary a bit with the weight of the hanger and a specific hammock design but once the ridge line length is set it should not change.
If you want to see what the ridge line does use a hammock without a bug net. Hang it between trees spaced at different distances and see how the hammock feels at each spacing. Repeat the experiment with a fixed length ridge line in place. I'll be very surprised if you do not see a difference. ;-)