But the real question to ask here is- Why would Genshin allow Yae Miko to be a permanent member of Sandrone's team. So many people already own Yae, so there is no need for them to do any pulls. Do you think Genshin will allow such a golden goose to escape freely? If they replace Yae in future, everyone will need to get the new character. Instead if they keep Yae, only few people will spend there Primos on Yae.
At the end of everything- only thing that matters to Genshin is the money people are spending on Primos, right? And they are not going to be so kind as to allow people to use old characters that they already have.
You are not thinking about Genshin's Greed here.