It improves the stats in some way. Armor has more slots, assemblers are faster, batteries have more capacity, …
The recipe is for using quality ingredients to guarantee at least that quality output.
The modules are for the random chance of getting a quality output.
Quality batteries aren’t too hard to make and really helped with the limited space on Fulgora before I got the foundations. Same with quality furnaces and generators which produce more from the same input.
I’m not familiar with what Suse is doing, but that doc seems to imply that there is a fundamental difference in the configuration between Gentoo and Suse.
I wonder if there is something in the Suse docs that describes how they get a rollback option into the grub menu.
I agree that the Gentoo wiki pages around btrfs and snapper seem a bit lacking.