[CLIENT] Illogical diversity requirement for dynamic queue

Whenever I'm in a dynamic queue of 3 (2 friends and me), it often comes to where they want to duo bot. So they will select bot/sup and sup/bot. However, I like to select fill cause I enjoy getting more practice with all positions. But for some reason, when they do their bot/sup and sup/bot, if I choose fill, it says we need a more diverse group. However if they do the same and I just choose 2 other positions like jgl/top, it allows us to enter queue.

Now, I'm almost sure that having a fill and a duo bot is more diverse than having a jgl/top and a duo bot. So unless Riot disagrees with me, that means one of two things. One, choosing fill should fit the diversity requirement in this case. Or two, jgl/top shouldn't fit the diversity requirement in this case.

If somebody from Riot could tell me how the diversity requirements are supposed to work, I would appreciate it.