I have to disagree. European teams go through more often because they are better than teams from other continents. That's the same reason why South American teams reach the round of 16 more often than other continents despite a similar number of teams in the tournament.

If there were two African teams per group, you'd have a much lower average quality for African teams. As it is now (32 teams at the World Cup, 5 from Africa), you'd probably find it a reasonable expectation that 2/5 African teams, so 40%, make it to the round of 16. If there were 16 African teams, you'd limit the number of spots for Europe and South America, but Europe's and South America's top teams would still be there, so 6/16 African teams going through would be a reasonable expectation because almost every group would have 1 or 2 teams from Europe and South America that qualify (plus Mexico); after all, if you have 16 African teams, you are bound to have some weak ones at the tournament and you know that Africa's top teams already have trouble to prevail. 6/16 is 38.5%.

Get it? The percentage metric is a fair one. The more teams a confederation has, the more teams will have to reach the round of 16 to get the percentage to a satisfactory level. The UEFA club and country rankings work similarly; countries who have only a couple of teams in Champions League and Europa League can work their way up in the rankings quickly, because they only need one or two successful clubs whereas the big nations need a few clubs do well every year to maintain their position. Having more Austrian clubs play in Europe would be detrimental for Austria's ranking, rather than beneficial like your argument implies. That's why the low number of African teams at the World Cup isn't a disadvantage. After all, the low number has never been a disadvantage for South America.