You're correct, I don't have it nor would waste a hard credit pull for it. And yes I do have some contempt for JMB as now being one of the weakest programs in the entirety of OW. It actually used to be quite decent but they gave in. NH had the last decent award chart in Japan but they've also ducked the same way now.

Flying JL itself I'm pretty sure you'd be better off credting to AA in premium cabins vs. JL. Their cabin multipliers are not great and status bonus is nearly the same as AAdvantage (comparing EXP to JL Diamond)

My main point was that many people would be better off with a Marriott Bonvoy credit card vs. ANY JMB card if wanting to earn JL miles. The Japanese Bonvoy card is actually quite excellent if one is eligible for it, and the US one is still likely better than the JAL USA card if just wanting to redeem via JMB (which has an awful international award chart these days).

Please inform me on how JL Diamond is more beneficial than AA EXP? I am quite certain that JL doesn't give international upgrade certificates with Diamond. So the should be basically equal EXCEPT AA gives upgrade certificates.