Earlier quoted context omitted.
That's amusing, and I wonder if this particular analogy was chosen deliberately. But I don't think there's anything wrong with it - it's designed to make intuitive sense to non-programming readers, not to be some rigorous description that can be automatically translated into optimal code.
Perhaps a different analogy would be better, e.g. ordering materials when building a house. If you can only order one material at a time, you would probably want to order the concrete for laying the foundation before ordering the roof tiles. Loading website resources is a lot like that (at least compared to the travelling salesman).
This still smells NP Hard. I mean, in practice for simple dependencies it is probably quite tractable, but this is a combinatorial optimization problem that seems pretty similar to an online modification to Job Shop Scheduling, where the material requirements map loosely to machine-task pairings that would be unblocked by orders, acting to make the problem more complex, not easier.