"Everybody probably agrees" - yeah right.
It depends how you judge "lesser". If you compare someone who got to where he got through sheer hard work and determination as well as oodles of talent, and who won the World Championship 9 years after he started racing on four wheels, in a team who had already decided to drop him the following year; then ask yourself how old was Schumacher, or Hamilton, when they started racing on four wheels, and compare the time between then and their first WDC I think you'll see it is a sort of impossible question to answer.
Anyone, and I mean, anyone, who is able to score more points than anyone else through a season, based on that year's scoring system, is a deserving World Champion - none of these guys are slouches! You could argue that 1982 (Rosberg) was not a particularly brilliant year, looking at the results. Was he undeserving? No!
Oh and there are one or two WDCs which were won using cars which were not... well let's just say, their interpretation of the rules was very questionable. If I recall, the 1994 Benetton had many questions asked at the time and since about it's legality. Couldn't possibly be true though, because it's never been proven...
Is the World Champion always the absolute fastest guy out there? No, of course not, but that just shows it's not just about out and out speed all the time. To win a WDC many things have to come together.
If I had to name champions I've always thought of as luckier than their contemporaries then Mike Hawthorn springs to mind, but I'll happily listen to the counter arguments... Damon Hill won many more races than Hawthorn in his championship year.