vilas, you can sequence the flightplan after the intercept as well.
If the extended centreline is different from the inbound track, as with most of our VOR approaches, every idiot will understand that you want the final approach track extended and not the runway QDM.
But I agree with you, technically speaking it is not the centerline. Try to change this habit in 2000 pilots who have been saying 'extend the centerline' for more than a decade.