I must admit I do like the humble flowchart
It actually forces tight code, but really it is replaced with pseudo code, then python once you have written a few flowcharts.
I was forced to write flow charts for GCSE Computer Science, and that was probably one of the only good things I received from education, though of course very rare to write one commercially. Still, in a commercial setting they are quite good to get over a complex'ish idea to someone who would not respond to pseudo code.
They tend to be done after the coding, by most coders, so their use in the design phase is a bit misleading - they are more useful in the documentation stage, to show users the flow of a process.
But, really I suppose we all use a hybrid diagram process, the real trick is that people (non techs) respond better to imagery than text. Personally, I subscribe to show me the data tables / structures and I can work out how the program should flow.