Perhaps UML ceased to be a fad for some, but to this day UML is still the best tool (and practically only tool) that helps describe and document code effectively and efficiently, from requirements to what classes comprised a submodule.
The "oversimplified and overcomplicated" jab makes no sense at all. UML is used to provide a view of a system without needing to go too much into detail (that's what code is for), and just because a bunch of people did a great job putting up a specification aimed at software developers intending to develop UML editora and code generators it does not mean it is overcomplicated". Anyone can use UML extensively if they can draw rectangles and lines on a piece of paper, or click and drag around in an editor. That's hardly a downside or a sign it's "overcomplicated".