@zachleat Of course, but I'm not sure what we're disagreeing on. Is the reason to delay hydration just because that's what <is-land>'s API wants to happen? I'm genuinely just trying to understand.
I like to think about WCs in terms of "what would native elements do". Would a native element defer hydration based on a blanket attribute? I don't think so! They might delay it given a specific reason, but that reason is part of the element's API, not a global option.