What about them? A weed is simply an unwanted plant. If they do no harm, why do you want to spend time removing them? Again, plant a good cover crop and don't weed. Your soil will be better, you will use less water, and there's no downside.

>(and snails)

Nothing about permaculture says you can't deal with snails. You can still deal with snails/slugs however you like. The obvious being simple copper wire or beer traps.

>Are you telling me, that you don't have to do weeding, like OP said, at all?

Correct. The only plants I pull out of the ground are root vegetables.

>So not in the protected greenhouse, but out in the open gardens, where there are seeds coming from everywhere?

Yes. Again, seeds coming from everywhere doesn't matter, because a dandelion in your potatoes doesn't hurt anything.