Population sizes of World Cup winners (2018)
Brazil - 5 times - Population 208m
Germany - 4 times - Population 83m
Italy - 4 times - Population 60.6m
Argentina - 2 times - Population 43.85m
Uruguay - 2 times - Population 3.4m
Spain - Once - population 46.56m
England - Once - population - 53.01m
France - Once - population - 67m
The obvious outlier is Uruguay but as the article in the OP points out, the early World Cups were somewhat farcical
Their 1950 success in context
The most shambolic World Cup of them all – in an admittedly crowded field – was undoubtedly the 1950 tournament in Brazil. Held in a fragile post-war landscape and hit by the late withdrawals of India, France and Scotland, the 13 teams who eventually qualified – some by default – were arranged into two groups of four, one group of three and one group of two, consisting of a single game: Uruguay 8-0 Bolivia. Facilities were basic, the schedule deeply unfair, the logistics a nightmare, and most amusingly of all at one game, Switzerland and Mexico – to their mutual befuddlement – both turned up wearing red shirts.
The 1930 World Cup held in Uruguay was contested by 13 teams and Uruguay only had to play 4 games to win it whilst the team they beat in the final had to play 5.
Population size is crucial, its a fact it is one of the correlating factors of success in international football. I don't even see how the point is arguable really.