Passengers are being treated like big babies at the airport.
Regular travellers know that when the information board says your flight is "boarding" it's not actually boarding. The airlines just want you to get down there to the gate and stand around like sheep for 15 minutes before they're actually ready to open the doors. This makes their job easier, but it's basically being dishonest and creates uncertainty in the minds of fliers.
When they say "final call", they generally mean the doors have just opened and boarding is just getting under way.
You want to know what the "final call" really is? It's when you hear your name on the airport's public address system. Now, I'm not advocating you should be so late that your name is called on the PA. But by being disingenuous with their language, the airlines put doubt and scepticism into the minds of regular fliers - many of us are unsure when the plane is actually boarding. More dangerously, many of us reckon we know. That's how flights get missed.
Worst of all there's no industry standard. I've turned up at some gates when the boarding message has gone out and it's been half an hour until the doors opened. Other times, it's been a mad scramble.