Why don't deliver on December, 28th?

It's allways the same, bad project management done with MS Project or similar products. Even if it is complex and painful it is possible to plan resources, their availability, and holidays, and to do a resource planing for each task. OK, your staff may change while working on a longer task, but you can document this through subtasks. And there are also switches to tell Project to let you solve resource conflicts by hand because of the nightmare of automatic reorganization. Relations, dependencies, dates, all have to be set very carefully. But when it's done allright your project management tool can help you to visualize and manage importand aspects of your undertaking.

But most time no resources are planned, no holidays are entered, the vacations are ignored. Only tasks with a rough duration estimation and some of the most importand dependencies. And where does it end? In nicely documented and communicated delivery dates like December, 28th. *sigh*

Is it really so hard?