If someone offers to resign, you can't decline them the offer, you don't have a choice!

You're right, people can choose to be stubborn morons. There's no rule against being a stubborn moron.

Let's say this game has a 7 day per move time control. My opponent is taking the full 7 days to make each move, and continues doing so from this position. The game could take nearly 2 months to finish.

It's pretty clear that in this case my opponent is being an idiot.

Now imagine that this is the last game of a tournament, and the other people enrolled in the tournament are enrolled in the maximum number of tournaments allowed, and have to wait 50 days before they can enroll in another tournament because some moron is refusing to resign.

Most of the time, when I tell someone "Do you really want to continue this, it's absolutely pointless?" they'll be respectful and stop wasting their and my time and resign.

Let me be clear: I don't expect people to resign a position where there's a very small chance of a stalemate or draw. I expect people to resign when they are obviously going to lose. If I'm up two rooks, I'm not going to screw up so badly that I'm going to give both of them away.