True. It took me years to realize that the most difficult thing is actually to systematically derive what to do in which order and concurrence, and that in any decently complex project, systems engineering (an art and science apparently long forgotten) methods are the only way to derive that in a sufficiently reliable way. The result is - no wonder - not just a gantt chart, but an n-dimensional model with multiple levels of detail. The PMI writings just tell you that you e.g. have to create a WBS, but they leave you all alone with how to derive something like this systematically. Accordingly, the many PM tools seem helplessly naive to me, where some computer scientists have simply built something that corresponds to the outward appearance of what they assume under PM.

I worked for many years on large, complex government projects and eventually started building prototypes for tools that would be useful (e.g. https://github.com/rochus-keller/FlowLine2 or https://github.com/rochus-keller/WorkTree); but you would have to invest a lot more development resources, and whether people would understand the tools and their usefulness (so there would be a market) is questionable.