Yes, PlantUML is very helpful in that way. I know this because I have used it in many projects. But Mermaid caught my attention because of its beauty and simplicity. I don’t know if you have tried to customize a PlantUML diagram with colors, positions and other stuff. I don’t have the patience for that. :p

Now, UML is a recognized standard, and it will not go anywhere. If you learn it, you won’t waste time at all.

So, I rather prefer mermaid for personal or small projects which don’t involve many people. However, if you need to diagram for work in a large company with established standards, then UML is your friend here.

In the end, we have options, and we pick the best tool for every job.

Good luck!

You can also try mermaid (http://mermaid.js.org/syntax/sequenceDiagram.html). There is a babel extension for that

https://github.com/arnm/ob-mermaid

For me the syntax is lighter and the aesthetics are nice and modern.