Gura maybe not so much, much of her Hololive success was due to her carrying her old viewer base into Hololive itself. That's why a lot of people who weren't in the know think her success was a booming, out of the blue thing: it wasn't. She had been an internet figure for a while back then.
Ame on the other hand had always been trying to do things. When she joined hololive she was the one instigating fanmade games, and the "small ame" model was one that she got from other people iirc because the official one was taking way too long. She was also the first to make a charity stream as well. Really, looking back, it feels like Ame was the one that was constantly trying to break the mold. Which kinda explains why in Advent you get girls who stick to what they're supposed to do, and why Hololive is trying to go for girls who are at least half asian now, and when they can't, they go for girls who are obsessed with idols and japanese pop culture in general.
