I would hazard a guess that on the 9mm guns, especially the sub compact G26 , that it has to do with the dwell time of the of the slide when under recoil...the static closed and open spring pressures can be measured, but I don't have one to compare with the older single unit can only speculate that it has more tension.. I'm sure the project engineers did (probablythe same guy that responded to my suggestions that there was no need to add additional length to the beavertail for people with large hands, and that a dovetailed front sight was not necessary)......a lot of new shooters are not instructed how to lock their wrist, and any short slide guns , not exclusively Glocks, are more prone to jamming... there is a certain distance of slide travel required, and certain amount of frame resistance needed to make them operate reliably...sometime there is just not enough time to allow the round to be stripped from the magazine and chambered
FWIW... I use a non captured stainless guide rod and single ISMI spring rated a couple of pounds higher than factory, and let it take a set... I