Well you get them as Arcanist for a reason. They are Arcanist techniques specifically, which is why Scholar also has them. Your complaint is more that Summoner doesn't fit as a branch of the Arcanist class, which is valid. As Summoners focus more on demi-primals it makes less and less sense that we are tied to the Arcanist class, to the point where Summoner should really just be its own thing. If they really wanted to they could just replace Bio and Miasma with primal-themed equivalents, but they seem to want to make sure that link to the Arcanist class is still there, and so Bio and Miasma (along with physick) are what we have.