It's amusing as fuck that people STILL didn't understand why Holo girls are as strong as they are.
I like to mention it as often as possible that Hololive greatest strength is
>the shared audience
>the interpersonal relationship between the girls
and more than ever that's being proved true here.
Marine is not doing anything special, all she's doing is to watch the hand made animations made by the fans of the girls.
Notice they're not necessarily Marine fans, each of them certainly has their own oshi.
But the interpersonal relationships between the girls make it so that when the create art for their oshis, more often than not the other girls ends up part of it as part of the "shared cinematic universe".
And Marine acknowledging that and highlighting that in front of her audience incentivises the artists to produce more of it, creating a positive cycle of creativity and public displays of appreciation in both directions.

That, incidentally, is why "outsiders" wants their favourites to be included in this "interpersonal relationship" as hard as they want, to a point of almost literally begging for it.
In their minds it would grant them access to this "shared audience" and elevate them to the same level of the Holo girls.
>it doesn't work, the audience likes what they like and that's Hololive and Hololive only for the most part
It's an interesting phenomenon to witness because it explains a lot of dynamics that are in play
>why the Holo girls are strong
>why they get so much artwork
>why OObeggars exist (be it homo, niji, phase, indie and whatnot)