"We can't explain it therefore we can't create it" doesn't seem like a strong argument, emergent behavior and whatnot.

Hell, the fact we don't know what consciousness is means that some LLM systems (or trees! or planets!) might already have it, and we'd be none the wiser. Not that I believe this, but as these systems get larger and more sophisticated it's an increasingly concerning proposition that we have no way to validate either way.