People have to train and city road is not best of surfaces. So it is very possible that somewhere someone already ran faster than 2 hours, just did not care to record it or announce it.
The article also talks about drafting and the role of 'pace bunnies' in setting a record. For those reasons, I don't think someone has gone out on a 42.2k run and broken the 2 hour mark.
There's also a financial incentive to run your fast marathon in a race, especially for the runners from poor East African countries who are the only ones capable of running close to the world record. The prize money is typically several hundred thousand dollars if you include the bonuses for breaking the course record and the world record, finishing faster than certain time thresholds, etc.