That's the convenience. I don't have to worry about the temperature. I drop it in the bath and I take it out at my convenience.
Nobody's gonna say that a circulator steak is bad. It's the second-best way to cook a steak. :)
I just keep a thermometer in for the entire duration of the bake time. Someone in this thread posted a screenshot of them doing the same thing with some sort of bluetooth thermometer.
I get what you're saying (I've got like 4 different circulators here, I'm not against them!) but the reverse sear is forgiving and flexible enough that I don't really even get a convenience win from it.
(For calibration: my modal steak is a Whole Foods ribeye or strip, unmodified except for being salted ahead of time).
We buy half a beef every six months or so (split with my parents, so I guess it's technically 5/7th's of a half? 5/14th's of a cow?). For a few hours on a weekend doing some prep/portioning, I can dramatically reduce the workload for several week's worth of meals.
Obviously there's other tradeoffs involved and different personal circumstances to consider, but for me the circulator wins out from a convenience perspective.