Ever since "A Single Pale Rose" aired, several of my theories have been disproven and a couple made completely obsolete (the difference being, the obsolete ones where never needed before the episode). One of those theories is my theory about how Robonoids were used to replace Rose Quartzes are field medics to heal cracked Gems.
Whist there was some controversy about whether our Rose was the only one with heal powers or not, the latest episode revealed that our Rose wasn't a Rose Quartz at all, she was Pink Diamond. Because of this it's now safe to assume she was the only Ge that could heal others.
But what happens to cracked Gems then?
Simple. Whilst Roboniods and their goo most likly didn't exist until Era 2, there would likly be some other kind of healing fluid on Homeworld. The difference between that and Rose's tears is that the fluid was likly not portable and not on Earth (where the actual war was taking place), meaning cracked Homeworld Gems had to be removed from Earth to be fixed.
A minor thing to note is that when watching "Ocean Gem" I was thinking that Lapis was trying to get back to Homeworld with a cracked gemstone. If Homeworld has no way of healing Gems then what would have happened to Lapis? It's mostly Lapis was so homesick she simply didn't consider what would potentially happen to her. (either that or she wanted to be euthanised because she was in so much misery, or planning on living as an Off-colour)
I agree, but I'm not so sure they would have to be taken all the way back to homeworld, It's likely they would have simply had to make their way back to some kind of deployment ship within Earths orbit. Also It's pretty safe to assume that the healing goo probably predates the robonoids atleast a little, right? I mean why create an autonomous deployment system for something that doesn't exist, granted the robonoids have other purposes and are assumably specced differently for these purposes.