You THINK it's easy. A nice clean set of boxes in a line with arrows. ... until you get branching. Exceptions/error branching. Subflows. Suddenly, you have a

You THINK it's easy. A nice clean set of boxes in a line with arrows. ... until you get branching. Exceptions/error branching. Subflows. Suddenly, you have a fully turing complete engine. The modern compromise is a DAG that hopefully guides a workflow to completion a la the halting problem. Anyway, there are a ton of piss poor ones with too many bespoke interfaces.