WC argument served well 20+ years ago when basically 4-5 teams tossed themselves the cup, football was played at 40% the speed & strength of nowadays, key players stayed on their countries powering their own national leagues and club seasons were short.
If you look at it by just logic, you are comparing a team performance that compete every 4 years for 3 matches at worst and 7 matches at best (qualifiers/continental cups aside) v/s teams that play a whole season worth of 2 tournaments & every-week league game at the same time.
This is not the same era of football in which one-man show dominated, you actually need solid squads overall.
A prime Messi would have still won Argentina that cup on his own. He just wasn't fit.