The most profitable BCNM fight involves 2 Ninjas. I've yet to even see an alternative setup that can even win it. It's more profiable than KS30, and just as you can't use KS fights to BS fights, you can't use BS seals for KS fights.
(BS seals are much more common.)
And forget skillchaining kirin. You spend so much time waiting for the opportunity, that you are wasting time you could be spamming nukes and weapon skills on it. You wind up killing Kirin slower. The only reasoning I could see behind it is a huge abundance of WHMs and a poor setup of DDs, to make them unable to deal good damage by just spamming. And no that includes melees, who have a good weapon for the job and thf SJ, and MNK/WHM with all their MND gear.
Not to be snobby, but I have talked to other LS before and they tell me how their kirins take hours, and they need like 35+ people.
I've taken down Kirin with like 20, post RNG nerf in maybe 2 hours. And with 28 people done it in like an hour.
Just to try and explain the effectiveness of just spamming on it. IF SC and MBs are better, I'd do them. It doesn't mean just because I chose not to it's hard, just not reliable.