Let me count the ways:
Strong abs? Dozens of better exercises.
Strong back? Dozens of better exercises.
Strong legs? Horrible choice.
So let's use the age old "exception to the rule" argument: Harry Hypertension, strongman, does Zercher squats thus Johnny Come Lately thinks he should do them to. Never mind the fact that Ol' Harry has been doing squats, deadlifts and presses, rows and chins and push-ups and dips and sled work for about two decades. But Johnny wants to bypass all of that because it's nice to have a lower body movement that won't crap the bed on him because he is weak.
No, he's got a built in excuse that it hurts his arms because every parlor trick is nothing more than a wall of cards. So instead of strengthening his body with full range movements, jumps, throws, running, and increasing his relative strength for the next 20 years, he is doing Zercher squats.
99.9999% of the audience that reads what I write has less than 3 years of lifting experience. So I 100% believe it best to steer them to something that is worthwhile, which is namely doing things that have been proven for the last 100 years. Namely balance.
I honestly don't really care what people do - but this forum has my name on it and if someone asks, I'll tell them my opinion. If someone loves the Zercher squat, so be it. The Zercher crowd is always butthurt, though. So it always gives me a good laugh.
Have a great Xmas or Holiday or whatever I'm supposed to say.