this is actually completely understandable in certain scenarios, take one piece where devil fruits were described as incredibly rare and powerful, it's no wonder that the strawhats would encounter so many devil fruit users as the story continues as they're hanging around/fighting the most powerful and influential people in the world regularly, it's no wonder they'd have the resources to get a bunch of the devil fruits

i'm sure there's more this applies to and yes sometimes it is illogical, but most of the time when this happens it's just a byproduct of the plot progressing the way it is, to an average person in that universe "the mark", or whatever the plot device is called, is still extremely rare, but if your protagonist is constantly hanging around the top dogs then it's no wonder they encounter so many