I’ve never gotten my head around the idea. Why is a hunk of meat, with liquid over it, cooked in a crockpot for hours, is somehow… a roast?
As in pot roasts? I guess that we got used to calling all hunks of meat that were cooked whole ‘roasts’ and the term stuck even when we changed the method of cooking 
Browned meat that is cooked in water is called braised. A pot roast is just a traditional term for a braised cut of meat. Meat that is just thrown in a pot of water is normally called “soggy”, as in a New England boiled dinner, or something like a corned beef. “Roast beef” is dry-roasted uncovered in an oven without liquid.
Ah, just reread the title. I see you’re familiar with braising. So your question is basically, why do we call it a pot “roast”? Probably because of the cut of meat, rather than the technique.
I’m concurring that it refers to the cut, not the cooking method.
In the UK, meat cooked in the oven is almost always “roasted”, while bakery goods cooked in the oven are “baked”. We don’t generally use “braised” for anything. So it could be a hangover from a prior version of English?
So that leads to the question - why is a chuck roast called a “roast”? I think if you actually roasted a big piece of chuck you’d come up with something dry, tough, and inedible - too much connective tissue, right?
I’d agree generally, but I eat braising steak, which you can buy in any old supermarket or butchers in the UK… Not sure what cut of meat it is but browned off in a frying pan then braised in stock in the oven for a couple of hours, it’s damn tasty!
We don’t? I use it all the time. Am I out of step with my nation’s culinary zeitgeist?
Bugger.
Go back 150 years or so, and meat cooked in the oven, dry or wet, wasn’t “roasted” at all, it was “baked”. To be “roasted”, it had to be turned on a spit.
Because it’s a roast cut instead of a steak?