Let me make this clear once and for all.
World Cups are not the yardsticks to achieve all-time greatness in limited overs format.
However, to achieve greatness in limited overs, you have to impact the game in some way or the other apart from the stats.
This is why Hashim Amla is not an all-time great in odis. He has great stats but lacks impact in odis. 30 years from now if poeple talk about Amla, they will remember him for his test exploits not for any of his one-day exploits.
For examples, Waqar Younis failed in World cup but he still is an ATG because he had one of the most devastating peak of all-time and impacted the game by mastering the skill of reverse swing and is remembered for those toe-crushing yorkers.
AB had an under-par WC but still is an ATG because like Waqar, he has been a pioneer of modern day 360° batting with those breathtaking shots which has established himself as the most toughest batsmen to bowl to in slog overs and also had one of the most devastating peak in odis. Only in PP, I see posters putting Inzy ahead of him. Outside that, people will take AB without any shadow of doubt simply because of having such great impact towards the game.
Now,imagine what if Kohli gets injured before 2019 WC and has to back out of that tournament and doesn't do much on his last leg in 2023 WC? Would you consider him an ATG or No? Yes, he will still be considered as an ATG irrespective of WC performance because he still had an impact towards the game by establishing himself as the greatest run chaser of all-time.
Amla didnt had any such impact and hence he isn't an ATG. If he was a clutch bat in LOIs though and performed in WC, he could have been an ATG because in that case his impact would have been quite visible. With no great performance and no match winning knocks in World Cup, he has no impact towards the game and hence is just a statistical marvel in limited overs.