Keep in mind that Sora/A-chan, highschool girls on a mission is quite possibly kayfabe.
@The Rrat ranted about it in the past, and made valid points.
But even accounting for that, A-chan was, of course, instrumental. From early tech support over saving Suisei's flatlining career and several other talents that were likewise on the verge of quitting. Even without the probable kayfabe origin story, Yagoo made Hololive, but A-chan (by way of Sora pushing her in that direction) shaped its culture. No A-chan, no Suisei as we know her. Possibly several other graduated members (Roboco, I hear?). A corporate environment much more resembling Nijisanji than the Cover we know.
A-chan, by virtue of her routine appearances on the Hololive channel, represented Hololive more than any other. Shaped Hololive culture from a time when it had two employees, a VR pingpong game and a single VA until it became the behemoth of today.
Filling her shoes isn't just a difficult task. It's plain impossible. Modern Cover is nigh infinitely different from the Cover she joined and helped shape. It's no longer
possible to have the impact she had.
By dint of seniority, by virtue of her close relationships with so many talents, by the sheer weight of her track record (again, Suisei would be but a footnote on par with Mano Aloe without A-chan's intervention, without her habit of maintaining close relationships with the talents...), A-chan's word assuredly mattered. Maybe less nowadays than in 2020, again because Cover has grown so much, but even so, not someone you can just brush aside.
And that's not something you can replace with someone new in the same role.
Nodoka's doing well, of course. It is clear that she is forming her own personal relationships with the talents, and is good at it.
But A-chan's sheer weight, her personal relationships within Cover (the benefits of starting at the company when the CEO could still bring pizza for lunch for everyone) are
gone.
Cover has changed so much since the Christmas miracle. A-chan, like Yagoo himself, like Gen 0, 1 & 2, is an artefact of a bygone time, when everything was smaller, more personable, more intimate.
Cover is growing up. And while I wasn't really aware of vtubing until 2021, and it'd be rich of me to claim that I miss the early Cover I never experienced, losing this bridge to a mythical past, a living reminder that this past happened, is still sad.
A-chan is a part of Cover's soul.
And as fondly remembered and cherished as I'm sure it is, that part is now gone.
