Yes, it makes a big difference where a fic is first published. I'm very intrigued by what factors (other than simply being a good story) go in to making something "popular" on AO3. I think how something is tagged matters, as does how long the fic is, and whether it's chaptered and posted in installments. And of course, popularity breeds popularity: once a fic gets enough kudos, it will float to the top of any list sorted by kudos and get even more readers and more kudos.

So yeah, just because a fic hasn't gotten many kudos doesn't necessarily mean it's not good. Indeed, capitu recced all three of these, so they must be reasonably good :)