I don't completely agree with this, Because winter in Qatar lasts for 3.1 months, from December 4 to March 8, with average daily highs below 26°C. The coldest month of the year in Doha is January, with an average low of 14°C and a high of 22°C. So this can benefit many countries competing for trophy.
Just looking at temperatures can be misleading. We have to count on the humidity levels and the thermal sensation. Which for those who are practicing a physical activity, are very significant elements.
Now, the fact that the World Cup is held in different places is also to create different difficulties for all teams. You can't just think about big teams.