Yes, you can get along without the remote, broadcasting thermometer. But the pit masters you speak of get to put their entire effort into watching the food. Usually, I don't have that luxury. I might be cleaning in the house, or mowing the lawn, or helping with some project, or even tying a fishing fly or two. I might be doing something with my DW. The point is, I rarely have the time to watch something Q'ing over the fire. That's where the thermometer comes in. It signals me when the food is getting close to the desired temperature I want. And knowing the proper temperature to get that perfect result varies from one item to the next.
We don't really need automobiles either. But I sure do appreciate the fact that I don't have to walk for an hour + to get to work. And that running water in the house feature, I could live without it. I have on many a camp out. But I do appreciate flush toilets, and turning on the tap for a cold drink of well water.
Some gadgets are excessive. But others help us get more done, help to increase our efficiency. And for the average guy or gal with a need to barbecue, that broadcasting thermometer might just be the ticket.
Do I need that gadget to produce good, or even great food? Certainly not. I lived without it for many years, and produced some excellent meals. And in fact, I don't have one now, as I broke mine.
But before I broke it, it sure was a handy tool.
Seeeeeeya; Chief Longwind of the North