Sounds more like they're saying: a knee is a knee, it doesn't have any magical properties. Build something that bends, and it will behave like a knee. I don't know how true that is, obviously.
If you're active, knee implants have to be replaced after 15-20 years, because they detach from the bone. Knee implants can harbor pockets of infections because they don't have an immune system. They are also more prone to dislocations.
They are objectively inferior to a healthy organic knee.
But most of the reasons why artificial knees are not as good as the real deal have to do with the fact that they're made of inert (albeit fancy) materials. They don't have the ability to continually heal and do tissue remodelling, which is what real tissue does.
I feel very optimistic when I think about this: we're limited, but I think it's absolutely wonderful what we're able to do.
Hope that reality isn't 50-years or more into the distant future.
> we're studying an "emergent" phenomenon
It's like saying that mapping all cells in human organism to addresses in memory will give us emergent human inside computer.
But still at abstract layer we just do not have a model of a working brain, we only have maps of neurons, not an actual "algorithm" or a model of all relevant environment interactions needed for a working brain or a set of "abstract instructions" needed for it to work. I think you are over optimistic about current state of our knowledge if we can't even model organism with few thousand neurons accurately. Imagine trying to do that for tens of billions of neurons and trillions of synapses, especially that we know brain doesn't work like an ANN at all[1].
1. https://www.nature.com/articles/s41583-020-0277-3/