I understand. But most people don't know beforehand if their connecting gate is a jetbridge or bus gate. And that matters, sometimes a lot. It has happened to me a couple of times that when connecting, I have had sparsely time, and I have run to connecting gate in the know that it WILL be a bus gate and therefore they typically board earlier than jetbridge gates, just to hear at T-35 "oh we were just about closing the gate, you are lucky to get in at last second". I say: "I am well within connection time, did you really think of bumping me?!!?". They reply "Yes but this is a bus gate and we have to keep our flight time slot"
Had I not run to the gate, they would have certainly bumped me!