Because of 1.) Jones' rivalry with Daniel Cormier 2.) Jones' legal/drug test problems 3.) Gus and his injuries and low career IQ 1.) Although Cormier has proven to be less of a threat to Jones than Gus stylistically, he got two attempts at Jones because of his credentials, and the fact that he beat Gus when they fought. 2 of Jones' last 3 fights were locked up, devoted to fighting DC. The other of those fights, against OSP, was meant to be against DC until DC got injured. If DC and Jones had fought in April 2016, when they were originally scheduled to rematch, and Jones won again, a bout between Jones and Gus would have been a strong candidate to be main or co-main of UFC 200. 2.) I think this is doesn't really need much elaboration. Jones has hardly managed to fight anyone due to his poor decisions. 3.) After the first fight with Jones, Alex fought a then lightly regarded Jimi Manuwa, and then made clear his intention to wait for a rematch. Bad idea. In MMA the world moves on without you if you stay on the sidelines. Keeping active would have done his case for a title shot wonders. Instead, he had a finish over Manuwa, a break, then he got put away by Rumble. He then lost to Cormier for the title. He found himself 0-2 in title shots with his biggest win being a decision over a really jaded Shogun Rua. He eventually got his career back on track, but he's been frustratingly inactive through those subsequent years. If he'd been willing to fight more often, and sometimes against opponents beneath him in the rankings, he could fought and likely beaten Ryan Bader, OSP, Corey Anderson and carved out an identity aside from being the guy who fought valiently in losing to Jones and DC.
The UFC was angling to make an immediate rematch but Jones publically said he didnt want it and he fought Glover Texiera instead. Later on injuries, Rumble KO and PED suspensions made it an impossibility.