This is wonderful.
In all honesty the reason is that superfights have proven not to sell PPV's because they are superfights. It thus doesn't make sense to keep doing them. Conor sold a superfight because he was Conor. DC v Stipe did the same numbers on the same card fighting other guys as they did fighting each other. GSP v Penn sold because of GSP and Penn being stars not because there were two belts on the line.
Champ v champ is not something people inherently cared about. Good matchups in divisions people care about do better numbers than sport wrecking superfights. These fights are awful as they put two divisions on hold at once and if they aren't making the UFC a shit ton of extra money like Conor did they are a cancer to the UFC's business not just the fans as the UFC loses a ton of main events for a main event doing the same or less. Cyborg is one of the biggest stars in the UFC, gave her a superfight with Nunes and now she has nowhere to go. With Cyborg it's different cause she had no division but a superfight means you're risking losing a champion doing main events.
But yeah TJ v Henry was a superfight as Soul mentioned. Did good because it was ESPN plus debut. Cjuedo v Moraes is a superish fight as the 125 champ is going to fight the 135 number one contender. It will do piss poor numbers, casuals don't even know who Moraes is, he's a fill in for TJ who was getting his rematch at 135.