The thing with young drivers from my view.

Money/sponsors and some talent takes you to the level where Rovanpera is atm quite fast (off course provided there is some talent in the first place). Getting from this level (~national rally champion) to the next level (can get top 3 in wrc) is harder, getting to win WRC rallies is even harder than that and championship is another level entirely.

Take for example Matt Wilson - never got past the first level, even though he looked almost as promising as Rovanpera early on. Likewise you could take Latvala and Mikkelsen who also had similar starts and now are "stuck" on the next best level for 2-4 years.

Which is why I react to people calling "young" drivers future champions. (Lappi, Rovanpera, Huttunen etc.)