> I can't believe someone took time to generate such a thing, as if it is useful to anyone

Thanks for saying this. UML is beyond useless, almost nobody understands it, almost nobody does it right and almost nobody uses it when they need to (because it makes no sense to them).

> UML is beyond useless, almost nobody understands it, almost nobody does it right and almost nobody uses it when they need to (because it makes no sense to them).

I completely disagree. UML is one of the best tools to communicate system designs and behavior in a high-level language that is easy to understand. Like everything in software engineering, you can make things very hard to understand or you can focus on making things easy to understand, and if you do not take the time to familiarize yourself with the basics them everything sounds very complex and useless to you.