It's an error to act as though these things aren't related IMO. Exposure to fewer virus particles means fewer nucleation points for an infection, which in turn

It's an error to act as though these things aren't related IMO. Exposure to fewer virus particles means fewer nucleation points for an infection, which in turn means that there must be greater replication to achieve the same viral load. If there's a causal link between viral load (or speed of onset) and severity of presentation, then reducing the amount of virus involved in each transmission will also reduce the severity.