Ascribing adult behaviours to a toddler doesn't make any sense though. Stubborn means you have a mission and you don't give in easily. It is generally deliberate and conscious and not motivated by necessity.
With a child that age, there is no conscious effort to stick to their plan at all costs (mainly to themselves, in the end) for some sort of gain. They are simply unhappy and they are therefore crying. They need something - not want, need - a want is forgotten within minutes, a need is not.
Four hours of crying indicates a need. We cannot measure their pain or their emotion, all they have is to cry, and all we can do is to try everything possible to stop them crying. Walking away - even if 'popping in' to them - is ineffective, or at least extremely inefficient, at accomplishing this.
I see it as my job to try and minimise the crying done by my preverbal child, as crying indicates he is unhappy. The quicker I can put a stop to it, the better for us both.
To hold out for many hours as some sort of battle of wills is pathetic. What are you trying to prove? That you're bigger than him?