I think I see the disconnect here. My assumption was that this thread is mainly concerned with relative BBQ newbies that need some tips on getting their BBQing into shape. On the other hand, Seifer appears to be talking on the level of semi-pro or at least a dedicated and experienced pitmaster.
If you are looking at relative newbies, chances are that they have both poor temperature control and incorrect readings. The majority of thermometers mounted on BBQs are by default wildly out of whack. Even when you do calibrate those thermometers, it is often only possible to do that to one temperature - 100C. If you are cooking with charcoal or wood (which you would be for real BBQ), you will need something like the Maverick to learn how to control temperature on your equipment.
I don't dispute that as you become more experienced, you can rely on the wireless probes less and less, but to get to that level they are a very, very useful tool. Case in point, for the last 8 weeks or so, I have done on the order of 20-30 cooks and used my Maverick exactly once. That was for a 20 hour (overnight) cook with lump charcoal. It was there mainly as an alarm, in case the temperature went out of range. For all the other stuff, a quick poke with the Aldi version of a thermapen is sufficient - mainly to confirm both the texture and temperature. Yes, I'm too lazy to setup the Maverick for things that I know how to cook with my Akorn. If I was using someone else's BBQ rig, I'd be putting the Maverick into action as the first item.