Pratchett is a comedian who is lampooning what people believe about fantasy, and backfilling in explanations to justify how a world that sits on the back of elephants on the back of a turtle doesn't just plain fall apart. (Pratchett even had a line in one of his earlier books when comparing how his world worked to the real world was that his world was something to the effect that it was created by a God of perhaps less technical expertise, but a much greater flair for creativity.)
Much as I admire comedians, I don't think I'd put Terry on
that level. But I suppose it depends on how you comparatively place (intelligent) parody in the spectrum of entertainment.
Also, he has described the decision to make the Discworld as it is as one of his big errors (he wanted somewhere "obviously fantastic", or words to that effect, when he started off what was originally lampooning the "bad fantasy" genre). That accomplished (for better or worse), he's now as often or not trying to get the world to work
logically. Albeit that this logic does have to contend with the possibility of magic, and the nature of the Discworld being flat and on backs of the elephants on the back of the turtle, etc.
For the former, he has produced a magically-imbued world in which
not performing magic is the biggest trick. Wizards and witches both do their own particular magics, indeed, but both practice their own version of "headology" in preference, and actual 'magitech' devices such as picture-painting imps have become mundane through their very ubiquitousness...
As to being (ultimately) on the back of a star-turtle... Well, just like you don't really have to deal too much with the reality that the ground beneath your feet actually curves around and lines radiating away from your current location would meet again in some antipodal point, very few Discworld inhabitants (save for the Krullians, most notably) actually have to
consider the turtle. (Indeed, the pre-reform Omnian religion had become very "Round Planet"-inclined, and the fact that "The Turtle Moves" (and thus belief in the existence of the Turtle at all) was an often fatally heretical point-of-view.)
Thus, hindered somewhat by its fantastical origins (and "being written by a younger, less experienced author", or words to that effect), the Disc has become a place of... rationality. As rational a place as you can have, of course, with magic
working (when it is used, or abused), various supernatural or supernaturally-capable beings (including one who TALKS LIKE THIS), and the necessary influence of the element Narrativium (or possibly the goddess Narrativia, although I believe she's more the active ingredient on
this world).
(My apologies, I just happen to have a high affinity with the Pratchett oeuvre, so I can quite easily go on a lot longer than I intend to, in matters such as these. I won't compound this by following up on the Tolkien-esque world, once more, or divert into the likes of Xanth or Narnia, at least not on this occasion.)
As to the rest, I don't really disagree. Although Toady has rather started with a different setup, so along the way to the "emulating everything, even down to the quantum level" path there are already many abstractions brought in. Forgotten Bests are conjured into existence without any parentage at all (the oldest known sentients also lack this information, although this information is available for
their descendants, if any). And for an individual creature, the game may indeed know that the lower limb of a being is attached to the (respective) upper limb at one end and (likewise) a hand, foot or alternate end-effector at the other, but if that limb is feathered (or leather-membraned or similar) and part of of a flying creature it does
not work out the fluid dynamics of the air it flaps through and assess the energy transferral in order to assess the flight capabilities of the being. If the creature is tagged as a flying one, it can (at least whilst it possesses a semblance of its flight-capable qualities, and consciousness) fly. If it is not tagged for flying, then even the most elaborate plumage atop the lightest (yet strongest) skeleton and muscular frame is mere decoration in that regard. So, for now at least, we can abstract away the need to have a CFD simulation (or even an X-Plane-like blade-element theory) applied, as being too messy a solution to something that can quite likely be waved away as unnecessary.
Maybe (though I'm not saying it is this way) there's a similar attitude towards excrement tracking...
I, for one, would like to see a better
information tracking system. So that you cannot just assume, once you inform one remote villager of your success in defeating some obscure threat from the other side of the world (moreover, one that he would
never have practically have even had a reason to know about) that your fame is instantaneously known (and believed!) by all other beings that you might wish to talk to... Perhaps a little effort should be needed to spread word of your deeds, seeding the story among a few (credulous?) individuals, and perhaps getting more of an "Oh... well... if you
say you've just killed a nest of vampires over in that other civilisation, I
suppose you'd consider it a trivial matter to rid us of
our pet peeve(!)" response. I would also imagine it viable (and maybe even essential, especially for new adventurers) to allow 'creative' reporting. Spreading a different
kind of 'crap', you might say.
And, anyway, for
none of the fantasy worlds we are discussing have we heard an echo of Carl Sagan's "If you wish to make an apple pie from scratch, you must first invent the universe"... Toady's probably the closest of all those so far mentioned, though, I suppose.