@Sadistic Senpai I thought about it.
BM was a yonko when introduced as great pirate and WB was a yonko and WSM.
Roger had that title before even being PK and we saw that WB didn't at the same time.
I think WB didn't have it because, despite his immense strength, WB was a captain very recently. So, regardless of your strength, as a captain, WB needed more time to actually achieve stuff with his newly formed pirate crew, the WB pirates, and accomplish many stuff before the title of "Great Pirate" stick with him.
On the other hand, Roger from the get go, from the beginning of is journey, he started as a captain and until this point of the flashback, and until he died, he never let go of his captain position. So, he made much bigger name for himself than WB who despite probably being on same level of strength to Roger, he was a subbordinate to another captain. And a subordinate does not get the same reputation as the captain.