Firefly is only popular because after almost a year of little to no pagbait involving cute girls (sorry kafka is not exactly cute and is a hag) she was a breathe of "fresh air". Everyother girl (besides kafka) was neutral towards you, or not pushed hard. Without it her numbers would be similar to pre penacony stats were. she had the least amount of fanart out of all the revealed characters despite being leaked since launch month.

This is why pagbait in ZZZ and WUWA fails to produce any meaning full content, because they keep throwing pagbait crumbs at self insert pagcels, so its no longer special.
Genshins pagbait while more popular than its ZZZ or WUWA counterparts still falls short of firefly for the exact same reason as above.