According to them Jack is more valuable than Joker.
Jack was a direct underling of Kaido who was getting killed in front of his eyes while Joker got destroyed within a day at Dressrosa. Joker was still a Shichibukai so I don't think it would benefit his position to have his ties to Kaido exposed by calling in help/reinforcements from Wano.
Plus the moment Joker was captured, you see Jack come to rescue him. It was just unlucky that Joker was escorted by an Fujitora, Tsuru and Sengoku. Maybe the marines understood his importance to the Beast Pirates and New World in general? Idk but there is a lot of room for speculation and theory crafting.
We see Kaido visibly pissed at his SMILE trade and Joker going out. We also see King and Queen, who probably manage all of Kaido's business for him, berate Jack for failing to secure Doflamingo in Act 1.
They clearly valued Doflamingo highly. It's just that they got
really unlucky at multiple levels.