AEM is a little sketchy though, you need to trust a flash drive to hold it, and make sure that drive doesn’t get overridden by a malicious attacker. Your link goes more into depth about the disadvantages
In some threat models, it's more feasible to protect a portable flash/SSD drive than an entire laptop.
In other threat models, laptops/tablets/phones could be physically secured in a safe, or kept under direct physical supervision.
Yeah, that’s what I was alluding to. I think the OPs point still holds here- both of those are quite a bit harder than the built in Mac solution