It's worth noting that the article is from December 2021, making it 1½ years old.

I've used C4 in different ways.

Using Structurizr Lite (docker): I do really like the "as code" aspect. The DSL is okay, the documentation of it not so much. But in the end, the tooling is too limited, and I've never come to terms with it. The diagrams becomes very locked in, and are cumbersome to export.

I'm not a fan of integrating SaaS solutions into the documentation workflow, but would really suggest that in favor of the Lite offering. Although I haven't used it.

Using C4 with ordinary tools: What I've come to use more, is using the conepts (and templates when available) with other, non-specialized tools. With Miro for example (there are templates). While not as cool as the "as code" way, it's an nice and accessible way of visualizing software systems.