A quote from your second link...
The London Marathon is seen as "everyone's race". World champions, Olympic champions, record breakers, national champions, celebrities, wheelchair entrants, fun runners, people running in fancy dresss, young and old all take part in the streets of London at the same time.
Again it manages to miss out the thousands of club runners who train hard throughout the winter hoping to shave a few minutes or seconds off a pb. We seem to drop from national champions to celebrities and fun runners with nothing in between.
It is still meant to be the no.1 UK athletics event, not a mass fun run.