But beyond that, the stick throws are much larger than e.g. on an Xbox controller, there's much finer feeling, the end stops are harder, the sticks can be held differently (search "thumbing vs pinching", both are used irl but the latter gives finer control). It's just so different. And you can't compare at all to using two full sized joysticks, which would mean full wrist movement.
Also, cheap gaming joysticks are terrible. Two high quality ones (VKB NXT or better) cost more than a high quality RC transmitter. It does not save money.
Physics aren't really realistic. They're all enough to get the absolute basics down (e.g. that camera uptilt means that pitch left/right needs a corresponding yaw input to keep the view straight). But then different simulators vary. The most common, fairly ubiquitous complaint, is that it's too floaty (real quads drop much faster without throttle). It's not just due to bad physics, it's also because to be commercially successful they have to appeal to gamers too, maybe even primarily. Then there's the finer points, like wind, descending into your own chaotic vortex, or how easy you crash when you touch anything (sims are sooo forgiving).
And of course every quad is different, 1" 1S, 3.5" 2S Li-Ion and a 10" 4S handle substantially differently, but if you haven't flown any for real then you won't know what is right.
(If you're looking for a radio, unless you know what you want, just buy a TX16S please.)
(There are exceptions to everything I said above. But this is the common case.)