One of the things that strikes me the most about Roger is that we don't know that he has legitimately beaten a top tier.
Xebec was defeated in a 2vs1
Shiki had to withdraw due to a storm
We don't know if he defeated Garp
He didn't defeat Big Mom
He did not defeat Whitebeard
It is curious that Oda did not show Roger defeating the strongest pirates of his time, at least he should have done it with Shiki, Big Mom, Garp and Xebec
In this way it seems that Roger became king of the pirates just because he found an island
Xebec was defeated in a 2vs1
Shiki had to withdraw due to a storm
We don't know if he defeated Garp
He didn't defeat Big Mom
He did not defeat Whitebeard
It is curious that Oda did not show Roger defeating the strongest pirates of his time, at least he should have done it with Shiki, Big Mom, Garp and Xebec
In this way it seems that Roger became king of the pirates just because he found an island