Mathematician and architect Christopher Alexander promoted the idea of pattern languages in architecture, https://en.wikipedia.org/wiki/A_Pattern_Language

Later the idea was promoted in software, https://en.wikipedia.org/wiki/Design_Patterns

Patterns as in design patterns, not patterns as in pattern matching

Nah, looks like another iteration of UML.

"no design necessary" kind of folk, eh?

Proper design has little to do with drawing hundreds of little boxes and arrows.

I've seen a lot of horrible designs bundled with visio diagrams made by "architects" and good designs described in a txt file made by system engineers.

Cargo Cult, "Design" edition. Take a bad idea chosen for unclear reasons and then detail the heck out of it.

Look for Gang of Four or GoF and the Wiki link already mentioned. None of these patterns are implementation ready though and need sculpting and trimming most real life use cases.