Unfortunately Cydia Substrate is closed-source meaning that it makes it harder for other jailbreak stores to compete with the likes of Cydia. However it seems that this is something that famed iOS developer Comex is hoping to change. Comex has recently announced and released an alternative to the Cydia Substrate called Substitute, which is an open-sourced project in hopes to make it as available to developers as possible.
According to Comex, “This ideal of openness is very similar to that of free software, and I therefore believe that it’s in the spirit of jailbreaking to make as much low-level stuff open as possible, both for inspection and modification by curious users (who, after gaining knowledge that way, might end up becoming quite valuable to the community).”
Some have accused Saurik, the creator of Cydia, for closing the software to prevent competition, which is something that Saurik does not exactly deny. According to him, “I do this because we are fighting a battle against companies—not just companies like Apple, but companies like Rock Your Phone and iMods—who want to see “open” be traded away for “ease of use” or “profitability”.”