I've worked retail. Pretty much every place that's worth working at has banned a few customers. Perhaps 1 in 1000 customers will be actively abusive towards other customers or towards employees.
I recall my first boss, who once had a customer push to the front of the line in a crowded shop. The customer rudely demand to be served. My boss was a very proper older southern lady, and she said, "Ma'am, you can also find [this product] at the grocery store across the street, and I encourage you go there." After the woman had stomped out, my boss turned the other customers and said, "Well, she wants us to have a bad day, and we're not going to," and she served the next person in line. I'm told the other customers practically cheered.
Of course, if you had told her that her product was a "piece of shit," she would have disapproved of your language but she would have refunded your money and replaced the product in an instant. She took quality seriously. If you were really rude about it, I suppose she might have "fired" you afterwards, though.
As a boss, you need to set limits about how badly your customers can act before they get (politely) booted. Anything less is inhumane to your employees. But this doesn't mean you should fire a customer over a bad Amazon review.
There's "refusing service", "banning customers", and then there's "turning off a device you've already sold to a customer after he's taken it home". There are not many goods/products/businesses who get away with doing that. Even Steve's "You're holding it wrong!" wasn't followed up with "so I'm gonna remote brick it on you"...
(Interestingly, Amazon have in the past remote-deleted Kindle books on people's devices - but for very much better reasons that "you were a bit rude in your review", and they _still_ copped a roasting for it...)
I've had one of my kindles replaced because it wouldn't connect to wifi anymore, and the rep said they are sending me a new one, and I don't have to send the old one back, but they are blacklisting it on their servers - so if I ever fix it, it won't connect to the internet at all.
It was a bit weird, but I guess acceptable in that situation.