There's also the factor of journey time being reduced by skipping stations with limited ridership. It would only be by minutes, but there's psychology at work there as well as actual time saving. *Some* trains could still stop, but not every one, maybe every third. That would also build in an extra buffer for keeping to a schedule. so if time is lost by an event at another station, it would be made-up by skipping stations with low ridership demand.
This is done with buses and streetcars, why not this line?