Agreed, but the rules still seem to make an attempt at being physics. Movement rates are dictated. Rounds are about 6 seconds. Bigger weapons have more inertia (do more damage). Heavier armor is more likely to stop weapons. Not accurate, no, and I think 5e took positive steps away from 3e's attempts at simulation.
I think I see what you are getting at but I disagree that they are really an attempt at physics. I think the D&D rules are an attempt at creating a heroic adventure game (not necessarily heroic as in everyone is a hero, but rather heroic as opposed to gritty like WFRPG). Heroic adventure typically entails some combat, so you need to know how to resolve that. Ideally, the rules will create the experience that the game is attempting to achieve.
For example, a high level fighter with full HP isn't going to get taken out by a random arrow from some no name mook. As that wouldn't model heroic adventure very well. Some people take this to mean that D&D characters are superhuman and can take inhuman levels of punishment, like being stabbed in the liver thrice in a day and walking it off. I don't much care for that explanation. I much prefer the explanation (as happens in much heroic adventure fiction) that the character narrowly avoided serious injury.
Similarly, you have damage by weapon size. A greatsword deals more damage than a dagger. Which is a fine abstraction for this sort of game, which doesn't try to model the relative reach advantage of most weapons, but realistically a dagger can kill you just a effectively as a claymore in the real world. In certain, less common situations, such as having a weapon to a helpless individual's throat, the dagger would actually be a better weapon in the real world. (To be clear, I mean that circumstance where someone is standing behind a hostage with a weapon to their throat, in which case a claymore would be quite awkward.) However, the rules don't really attempt to cover such a situation for the most part. I think it would be odd to extrapolate from such rules that in this world everyone prefers to hold a great sword to someone's throat, rather than a dagger. IMO, the more reasonable conclusion is that the weapon rules weren't designed with that scenario in mind, but rather for more straight forward combat scenarios, and that a DM who wants to have such a scene will need to use something else (likely of their own devising).
In other words, they're only physics insofar as they are trying to recreate a reality within the imaginations of the players, and even then I think they're generally a far too gross oversimplification to be considered actual "physics". Simulation might be more accurate, though even here I think it's important to make the distinction that what is being simulated is the fiction of the game, rather than the game world itself.
