You are all welcome to join me in my own personal head canon of what is going on with the midiclorians.
They don't produce the force, or anything like that, they are just attracted to strong force users, so the stronger with the force you are, the more congregate in your blood.
One thing the prequels were supposed to show, but largely failed, was the old, stagnant Jedi order, and I use midiclorians as part of that narrative. Sometime long in the past the Jedi figured out they could get a sense of a person's connection with the force by looking at the number of midiclorians in them, then over the generations it turned into thinking they were what actually powered the force.