When I need to create diagrams for anything (systems, code architecture, component design, etc) I reach for OmniGraffle on macOS. I've tried to use other tools, but it has served me well for years.
There was a period in which you could rely on almost everyone to have it, which made it an attractive, convenient and low friction way to share diagrams that people could edit and update.
I do architecture work here in NZ and Visio is still ubiquitous here - it's part of the standard design/architecture toolkit. Usually the only discussion is whether you need the Pro or Standard licence (Pro is typically only required to integrate with external data sources).
Did it go somewhere?
(I generally prefer more declarative diagramming now — mermaidjs is my go to — but Visio is still around and widely used.)