It should.

But it isn't.

I don't get it. You are a progressive voter. You agree the difference should be enough to make you vote Democrat, yet you don't. Why?

The rest of your argument rests on the assumption that moving the policies of a presidential candidate is easier than moving individual votes. But how can that be the case? The positions a presidential candidate take are determined by a lot of very powerful, sometimes mutually exclusive interests. The positions a presidential candidate takes are the results of a lot of work and negotiations among these competing interests. Of course it is incredibly hard to change the policies of a candidate.

On the other hand, individual voters like yourself have two choices, and it seems reasonable you would choose the best of the two, or the least bad, if you will. You yourself said that the differences between the two choices you have should be enough to convince the voter to choose the option closer to their ideals.

So it seems to me that convincing individual voters is a much more efficient and likely to be successful strategy than trying to change the policies of Kamala.