I know that I am jumping far ahead, but can someone explain and remind me about BMF belt and title. Wasnt it like a special belt that was challenged between Masvidal and Diaz, and it supposed to be one time challenge/belt/title? I mean how can it travelled from Masvidal to Gaethe/Poirier? Sure they arent most BMF in UFC 
Now on UFC 300 Gaethje is defending this title Title that is not even in UFC ranking
Now on UFC 300 Gaethje is defending this title Title that is not even in UFC ranking Well, I know that the BMF is a special belt but for some like Masvidal, Porier, and McGregor this belt meant something them but it is just a special belt for fighters that don't want that belt or holds real significance to them, but for sure it is one of the additional belt that a fighter can take if you won that fight and that BMF belt is at stake and for some fighters this is a significant something for sure an additional Belt and collection for them.
Somehow I dont believe fighters are really that happy to get BMF belt instead of division champions belt
As I doubt it has any value outside UFC. I even think that other fighters might laugh at BMF holder. Like he isnt able to get a real belt, and UFC game him this Also there are no much competition to get this belt. It is like beat one guy and get a belt. Also look at Gaethje face when he got it. Not so happy at all. As to collecting belts, I believe every fighter has a huge stand of trophies that they get during their career. One more or one less reward it does not matter if it isnt a champions belt/trophy.