Yes, they are probably most useful to me for the IDE completions and docs as well. Raymond Hettinger gave at least one talk [1] where he discussed how there are tradeoffs: reasons why you might use them and reasons why you might not. At the end of the day you can pass whatever you want to a function and the only reason to use types if they make your code better—but there are other tools that might be more worth your time in some situations.
THIS. This is why I started using them, along with standardizing my docstrings. Enormously helpful when you're trying to remember what the function is expecting to just hover it and find out.