> In short, an interface should not be interactable until a few milliseconds after it has finished (re)renderingI was a console game developer working on UI for many years so I am deeply familiar with the problem when a UI should be responsive to input while the visuals are changing and when it should not.
You might be surprised, but it turns out that blocking input for a while until the UI settles down is not what you want.
Yes, in cases where the UI is transitioning to an unfamiliar state, the input has a good chance to be useless or incorrect and would be better dropped on the floor. It's annoying when you think you're going to click X but the UI changes to stick Y under your finger instead.
However, there are times where you're tapping on a familiar app whose flow you know intimately and you know exactly where Y is about to appear and you want to tap on it as fast as you can. In those cases, it is absolutely infuriating if the app simply ignores your input and forces you to tap again.
I've watched users use software that temporarily disables input like this and what you see is that they either get trained to learn the input delay and time their tap as tightly as possible, or they just get annoying and hammer inputs until it gets processed.
And, in practice, it turns out these latter times where a user is interacting with a familiar UI are 100x more common than when they misclick on an unfamiliar UI. So while the latter case is super annoying, it's a better experience in aggregate if the app is as responsive as it can be, as quickly as it can be.
Perhaps there is a third way where an app makes a distinction between flows to static context versus dynamically generated content and only puts an input block in for the latter, but I expect the line between "static" and "dynamic" is too fuzzy. People certainly learn to rely on familiar auto-complete suggestions.
UI is hard. A box of silicon to a great ape is not an easy connection to engineer.