Almost no Apple interactions are without animation. It's actually hard to find something that's NOT animated on Android AND iPhone. For most users, the iPhone is one of the gold standards for "good feel".
Some people like the unrealistic jumping of no animation, which is totally fine. Some people want it to "feel like a computer" not how things actually behave in the real world. It's taste. Animations that are too long or too noticeable are bad taste. But animations themselves are not bad.
Switches in the real world tend to snap almost instantly from one end to the other. That is the defining feature of switches – that they don't have a slow transition between the states. This animation stuff isn't realistic, and even if it was that isn't an argument for it.
But when you move a switch like the ones demonstrated here in the real world, you have the haptic feedback of moving the pin physically, of it "snapping" into place. And that's how you know that your switch toggling was successful.
The "digital switch" does not have that. You usually don't even "move" it, as in "move the finger over the screen", but you just touch it. And your finger obscures the UI component in the moment you touch it, without any haptic feedback (except for your finger hitting the screen somewhere, but that does not necessarily mean that the switch has toggled). The animation replaces this missing haptic feedback, by your eyes seeing the switch moving, when you remove your finger after touching the screen.
I agree more with James K on this, but see your point too. Maybe this should be abstracted away such that each person can set their own preference which would be applied across all websites. Similarly how some of them respect your theme (dark vs light), they could be made to respect the animations, so that all toggles behave the same way (fast animation / smooth animation / instant).
The transition is already there, on the actual switch (or the deformation of the fingertip with touchscreens). The animation is a second transition played after the first one is already complete. That is not realistic.
There are not many animations on iOS nor MacOS. What they are is movement that corresponds to the users movements. Like opening exposé with the touchpad on MacOS is not an animation, the windows follows the movement of your fingers. Likewise scrolling is not an animation, because it follows the users movements.
Some people like the unrealistic jumping of no animation, which is totally fine. Some people want it to "feel like a computer" not how things actually behave in the real world. It's taste. Animations that are too long or too noticeable are bad taste. But animations themselves are not bad.