Can't see a problem, merely using it as an example to show there have been times when there were 6/7 full Factory teams, and approx 20 Factory drivers. Just go back to 2001-2003 and Mitsubishi, Peugeot, Ford, Citroen & Subaru all won events. It obviously couldn't last.
You might want to look at the latest version of the WRC game - WRC4. It features 16 car models and 65 drivers, ostensibly from the 2013 season. If you looked at that in 20 years time, you might imagine that 2013 had been a halcyon year for the sport. But we are probably straying from the topic!