You got to think, the rest of the SeeDs can use GFs as well, and they're a global force.

(SPOILER)plus they don't have the ragnarok, so going overworld is a lot more annoying. They don't usually even have the mobile garden;P

plus, if they didn't do that, you'd be stuck with dead GFs all the time if you overuse them in the beginning. wewt. Or something, I dunno. I only use the petshops to grab the petpal magazines and esthar's for all those stat+40% items to refine