Since Kepler, science is not about mechanism but about prediction. There is often a rather fetishistic disdain of mechanism, that gets relegated to philosophical, coffee-table curiosities. See, for example, the various mechanisms that explain Newtonian and relativistic mechanics. Have you heard about them? Probably not; nobody cares, as the theories allow to make all the predictions than you need, and you do not need anything else.
The fact that there is no mechanism to explain a phenomenon that you can predict is not a problem. It may be a shortcoming of our understanding, but not in any case "scientifically indefensible", as you claim.
And that's OK.
Since Kepler, science is not about mechanism but about prediction. There is often a rather fetishistic disdain of mechanism, that gets relegated to philosophical, coffee-table curiosities. See, for example, the various mechanisms that explain Newtonian and relativistic mechanics. Have you heard about them? Probably not; nobody cares, as the theories allow to make all the predictions than you need, and you do not need anything else.
The fact that there is no mechanism to explain a phenomenon that you can predict is not a problem. It may be a shortcoming of our understanding, but not in any case "scientifically indefensible", as you claim.