Can't help but think that the tern 'Graduation' is from a Vtuber career being similar to a time in school or training where you go in to develop some capability that you didn't have before and after a while expect to move on to either a new identity or a new career altogether. For most of these oldschool faces it would be leaving with new confidence and/or industry connections as long as they were not forced out by a real disaster.
And yet you'd think from peoples' responses to the Graduation news that they expect a specific Vtuber identity to be a lifelong thing. I don't think most of the talents themselves go into it expecting it to be the last thing they do until the day they full on retire so the number of comments to the tune of "What will my life be after you're gone" directed at the character is quite concerning.