Trying to think of a quick analogy, it's a bit like saying that you are mowing your lawn with scissors and finding it slow and frustrating and don't know whether it is because the scissors are blunt or because your fingers aren't strong enough.
I see your point but I don't agree, because that's not my question. I'm not asking about getting the full experience; my question was that I'm getting what look like power readings that are not daft (and I'm not bothered about getting them exact), but they seem to be producing speeds uphill that differ substantially from what I'd expect in real life (i.e. barely moving when I'm expecting pretty slow). I was just testing the idea that Zwift is a bit hard on low-end riders, or of course that I might have missed something.
In summary, three-and-a-bit miles in nearly two hours on an output of around 1W/kg didn't seem right, but the output looks reasonable. It could still be self-delusion of course, and quite possibly is.
If I were right, then no set-up would necessarily make a difference to the effect. I've since done some more tests, and I'm not sure - I did the hilly loop and the results were not quite as bad (even when on gradients the same as on Muir and the Mountain). As a basic test, I'm noting power and gradient and sticking them into a cycling watts calculator to see if they're in the same ball-park.
For me, the benefits of a full set-up would be a rather separate question. I am actually unconvinced. What I do is to pedal a constant gear, with constant resistance, at a sustainable range of power, and let Zwift simulate the resulting way that speed varies with gradient. If I added a high-end set-up, the resistance would increase on virtual hills, and I'd compensate with gears to get back to my sustainable power range. So, if I imagine that pedalling just got harder and I just geared down, then everything including my cadence appears to be the same in both scenarios. Again, this is a different question, but I've not yet spotted what's different apart from my approach taxing my imagination a bit more
No doubt the eventual way to resolve that one will be to borrow a clubmate's set-up, some time after social distancing rules allow riders into each others' pain caves. In the meantime, I think I'm stuck on my mild discomfort patio outside the dining room window!
Really sorry if my responses are making people feel that their efforts in commenting are unappreciated; they are not.