pawel7777, I was more thinking about situation with Figuiredo vs Moreno, Conor Poirier, possible Conor vs Diaz 3, and other fighting series. Imho a real fan would watch any fight where his favourite fighter fights. And the situation with Volk for example and others go to other division for a fight. Each division has perhaps 100+ fighters, but no, fighters prefer to go to other division for more challenge, or because they have beaten everyone in their division (sometimes for 2 times).
Maybe they search for big names in other division. But in past, every division has enough big names. Nobody jumped here and there for a better fight.
Sure, there are dozens, if not hundreds fighters in each division, but the top fighter (or champs) will not be matched up with anybody ranked below the top 10 or the top 15. If they did, the purpose of rankings would be moot.
I'm sure UFC had figured out methods to determine what match ups will yield them the most money, which should go in line with what the fans prefer to see. And of course superstars like McGregor will be picky in choosing/accepting their opponents, but that's a different story.
But looking at Volk, I perfectly understand why he decided to jump up (even only temporarily). He already beat the top contenders (some of them multiple times) so it's either this or fighting lower-ranked guys that haven't yet proved they deserve the title shot. I don't think anyone outside the top 6 should be fighting for the belt, as, sport-wise, that's simply unfair. Luckily in that division we have Topuria who moved up to the top 5 contender and will be fighting Volk next, he's undefeated and looked really good in his last few fights.
But there individuals, that became champions or have a title fight in just 3-4 fights. And they start their journey unranked. Look how I see current situation. Take any lightweight or lower division. There are fighting tiers. Champion-top6, top7-top15, rest of division. And these guys fight between each other all the time only. If you are a good fighter, maximum you would achieve is being among "rest of division". Maybe Gods of random be kind to you, and someone from top15 will withdrew from fight due to injury and Gods will be double kind to you and you would be selected by match makers.