How so? Presumably this is just pulling the OSM data from 2007. Remember that until late 2007 every data point in the system was from user collected GPS traces, and that they only had ~9000 registered users at the time.
Some roads look strangely incomplete. But looking it at the point that the city I linked was probably done by a single person it makes sense.
The growth must have been unbelievable back then. When I created my account in June 2008 I only found very few streets in my city in Germany that had not been mapped yet.
That varies very much country by country - some have had mass imports from other open sources (e.g. open government data), which has helped enormously with streets, roads and suchlike.
It was glorious - those halcyon days of spotting a missing village or suburb and spending a day with GPS catching all the roads and footpaths.
"That bit doesn't connect up - Ah ha!"
Looking at the data in my vicinity, I would say no exaggeration is taking place: after all, you could fork the project and check it for yourself; this is the atrociously poor coverage which I remember OSM had in 2007.
What this shows is how much it's grown, and how much better it's gotten.
It's demonstrating the difference in quality of data, not city development.
Not really. OSM started out with a blank canvas. 2007 was still early days.