They hire people based on their talents and potentials, what can they bring to the table, not because they are a Hololive fan. Being a fan is a plus but it's not a requirement. Some girls also didn't give much of a shit about Hololive either like Luna, Rushia, Mori, or Kronii (keyword: didn't).
I think we can agree that FWMC was a golden hire since they've got everything, but it's still too soon to say anything about Shiori.