You could blame Robin, of course. But the part about consciousness doesn't actually look like confusion to me:

So it actually is possible that we could pawn off the only non-linear phenomenon in all of quantum physics onto a better understanding of consciousness. The question "How many conscious observers are contained in an evolving amplitude distribution?" has obvious reasons to be non-linear.

(!)

Robin Hanson has made a suggestion along these lines.

(!!)

Decoherence is a physically continuous process, and the interaction between LEFT and RIGHT blobs may never actually become zero.

So, Robin suggests, any blob of amplitude which gets small enough, becomes dominated by stray flows of amplitude from many larger worlds.

A blob which gets too small, cannot sustain coherent inner interactions - an internally driven chain of cause and effect - because the amplitude flows are dominated from outside. Too-small worlds fail to support computation and consciousness, or are ground up into chaos, or merge into larger worlds.

I alluded to this in the quantum-randomized memory discussion, when I said the configurations we were talking about all seemed to have equal amplitude. (So if we find ourselves definitively living in one of them through observation, Mangled Worlds does not appear to change that earlier question). Then another commenter suggested I read about Mangled Worlds. So clearly someone's missed something.

the question of how many worlds can be answered pretty well by ~2 to the power of the average number of decoherence events since the beginning.

Deocherence evernts aren't well defined .. they are always FAPP. That;s the source of the problem.