That’s the joke. He’s taking something obviously not important and turning it into a puzzle pedantically. If it were an important thing like a train bridge it would be less interesting
This track transports hundreds of Duplo citizens and various other toys daily. Damaged parts will not be able to be replaced until next birthday or Christmas, leading to significant delays. Furthermore, if the train were to snap mid play session, a citizen could be flung into the wall leading to loss of limb, which are not easily fixable like Lego minifigures. The train track is a critical part of playroom infrastructure and thus affords extra scrutiny.
This is what I love about the whole discussion. In some sense this is so utterly trivial, but I imagine the kids would be pretty upset if they broke a piece of the Duplo too. And I love that we've all absolutely nerded out on it, and gone in a dozen different directions with the discussion. It's just fun and, what makes it even more entertaining, is that so many people have engaged with it - as I write this it's literally at the top of the front page, where it's already been for at least a couple of hours, and closing in on 600 points. It's a great and positive conversation, and it's certainly added a bit of happiness to my day - I suspect lots of other peoples' too.
It would still be interesting as a train bridge, just for different reasons. The reason bridge you know that lives and material are on the line. For the child's train set you realize that there are deep and abstract principles underlying even childish things.
Duplo pieces are extremely durable so I wouldn't worry about them getting broken (as my poor feet can attest). If else one should be careful because with enough tension one piece may detach from the track and fly around hitting somebody.
Duplo, while expensive, is a consumable, if you look at it through this old man's eyes.
Now that that's out of the way, I love all the answers here.