Because whilst we have both Merab and Aljo sitting out, you have the rest of the division all fighting each other with no actual path to the title. It's 170 all over again. The best should just fight the best. If Aljo had won and moved up, it's a non issue. Aljo isn't going to move up and shouldn't hang it up.
Sean is also going to sit on that belt for ages.
Merab will reefuse to jump over Aljo. Aljo will want a full extended camp after feeling rushed in the last fight. Merab will help for that camp, minor hand injury (usually takes ages to heal) will became aggravated. Then if Aljo beats Sean, the UFC will do an immediate rematch because they want Sean as champ. Merab still waiting for his shot and the rest of the division has all had 2-3 good wins with a bunch of contenders waiting in the wings for a shot knocking each other off.
Now it's 2025 and the division hasn't moved forward in any meaningful way just because 2 guys didn't want to get paid to fight like they do for free every single day.