If you are doing any architectural work, whether at the software or infrastructire level, I fail to see how you can deal without diagrams to 1/ understand interactions between all system components 2/ make your changes understood and validated by relevant people.

Granted I speak about real, useful, technical diagrams, whose purpose is to convey useful information and highlight data flows. Not marketing diagrams you may find on marketing presentations, but this is not what this discussion is about.