You also often have ingredients or intermediate products that are used in more than one step so a tree is not ideal. You could duplicate those ingredients/intermediates but that would not be helpful.
And for more complex meals, time planning becomes more important so that everything is ready to serve together.
To be honest, I kind of prefer when a recipe treats duplicate ingredients as completely separate. Rather than that "use 300g of the butter here, use the rest here" approach which is harder to follow.
That works well for a basic off-the-shelf ingredient, but what if you needed a complex dressing/sauce/broth/marinade/spice mix that was later used in multiple combinations. You'd want to make that all in one batch.
Some dishes require more overlap, which will be tricky to write in this format.
E.g. taking the pan juices and turning that into a sauce. It's a separate process/dish, yet wholly dependant on the other process completing a critical step.
And for more complex meals, time planning becomes more important so that everything is ready to serve together.